Final Program Sensing Motion for Action

Transcription

Final Program
Sensing Motion for Action
A tribute to the career of Geoffrey Melvill Jones
Date & Venue
July 13th & 14th 2013
La Citadelle McGill Residence
410 Sherbrooke West
Montreal, Canada
Conference Chair & Organizer
Henrietta L. Galiana
Program Committee
Henrietta L. Galiana, Henrietta.Galiana@mcgill.ca
Kathleen E. Cullen, Kathleen.Cullen@mcgill.ca
Daniel Guitton – Daniel.Guitton@mcgill.ca
Attached are a 2-page symposium overview, followed by
the schedule and all presentation abstracts in chronological order.
Please contact one of the team above for emergencies or corrections.
Presentation Schedule
Saturday July 13th AM: La Citadelle Lounge (Top floor)
Podium Session I: Learning, Adaptation & Compensation
8:30-10:15
8:35-8:55
Geofffrey Melvill Jones
Adaptive Interactions Between Vestibular and Podokinetic Systems During Curved Locomotion
8:55-9:15
Serge Rossignol
Spinal Plasticity studied after spinal lesions
9:15-9:35
Christina Hui-Chan
Maximizing neural plasticity: Combing peripheral stimulation with central command to
enhance motor recovery in stroke
9:35-9:55
Carlos Gordon
A new approach to prevent backward falls due to imbalance
9:55-10:15
PP Vidal
Une histoire de grenouille tordue – Story of a twisted frog
Coffee Break
10:15-10:45
Podium Session II: Posture & Locomotion
10:45-12:30
10:45-11:05
Fay Horak
Turning is more difficult than walking straight
11:05-11:25
Gammon Earhart
Turning point: How experience can modify trajectory
11:25-11:45
Caroline Paquette
Steering gait mechanisms in the human brain
11:45-12:05
Robert E Kearney
New methods for estimating joint stiffness during posture and locomotion
12:05-12:15
Alain Berthoz
Celebratory message from Paris (5 min video)
Lunch
in Mezzanine 2nd Floor
use stairs down to posters
12:30-13:15
Saturday July 13th PM: La Citadelle entrance level Lounge
Poster Session in RC Lounge (rez-dechaussée / entrance level)
Coffee/juice remain available in Mezzanine
13:00-16:30
Note: See Poster list provided at end, grouped into themes
Banquet
La Citadelle top Floor Lounge
Will include short presentations and kudos…
18:30-22:00
Page 2
Sunday July 14th AM: La Citadelle Lounge (top floor)
Podium Session III: Sensory-Motor Interactions
9:00-10:45
9:00-9:20
Laurence R. Young
Models for adaptation of the VOR
9:20-9:40
John Leigh
Human translational VOR during combined rotations and translations
9:40-10:00
David S. Zee
Effects of the Magnetic Field of Strong MRI Machines on the Brain
10:00-10:20 Henrietta L. Galiana
Reaching with the eye & reaching with the hand – Common principles
10:20-10:40
Daniel Guitton
Human eye-head gaze shifts preserve accuracy and spatiotemporal trajectory profiles
Despite long-duration torque perturbations that assist or oppose the head
Coffee Break
Podium Session IV: The Vestibular System
10:45-11:15
11:15-13:00
11:15-11:35
Kathleen Cullen
The neural encoding of vestibular information during natural self-motion
11:35-11:55
Ruth Anne Eatock
The impact of low-voltage-activated potassium channels on signaling by type I hair cells and
calyceal afferents
11:55-12:15
Dan Merfeld
Subjective Detection of Vertical Acceleration: A Velocity Dependent Response?
12:15-12:35
Richard Lewis
Central vestibular processing investigated with electrical stimulation of canal ampullary nerves
12:35-12:55
Jay Goldberg
Cellular Basis of Discharge Regularity in the Vestibular Nerve and Its Impact on
Encoding Efficiency
Lunch in Mezzanine 2nd Floor
13:00-13:45
July 14th Sunday afternoon Posters still accessible in RC Lounge until 16:30 if desired, and meeting room Lounge
remains informally accessible if any attendees wish to have ad-hoc discussions.
Page 3
POSTERS List – View Saturday & Sunday pm
(put up Saturday morning, remove by 5pm Sunday, presenter underlined in multi-authors)
A - Learning, Adaptation & Compensation
A1 - Yoshiro Wada
Changes in head tilt perception and ocular counter-rolling under both microgravity and
hypergravity induced by parabolic flight
A2 - Mark Shelhamer
Predicting Sensorimotor Adaptation Ability through Fractal Time Series Analysis
A3 - Hans Van der Steen
Sensing and memorizing motion for action
A4 - John Simpson
Floccular climbing fibres: Their light and dark sides
A5 - Donna Mergler
Neurophysiology applied to epidemiologic studies of environmental toxics: mercury and manganese
B – Posture & Locomotion
B1 - Block EW, Fletcher WA, Horak F, Goodworth A and Melvill Jones G.
Curvature of the Locomotor Trajectory is controlled by the Ratio of Angular to Linear Components of
Podokinetic Nystagmus
B2 - Block EW, Fletcher WA, Horak F, Melvill Jones G.
Synchrony of Linear and Angular Components of Podokinetic Nystagmus During Curved Locomotion
B3 - Marina Martinez, Eléonore Serrano, Paul Xing, Hugo Delivet-Mongrain, Serge Rossignol
Role of dorsolateral pathways in locomotor recovery after spinal hemisection in cats
B4 - Stephanie Haggerty, Amy Wu, Arthur Kuo and Kathleen H. Sienko
Effects of Optokinetic and Galvanic Vestibular Stimulation on Standing Posture
B5 - Diego Guarin Lopez, Kian Jalaleddini and Robert E. Kearney
Identification of a Parametric, Discrete-time Model of Ankle Stiffness
B6 - Seyed Kian Jalaleddini, Robert E. Kearney
Subspace Method Decomposition and Identification of the Parallel-cascade Model of Ankle Joint Stiffness:
Theory and Simulation
B7 - Ehsan Sobhani Tehrani, Kian Jalaleddini, Robert E. Kearney
A Novel Algorithm for Linear Parameter Varying Identification of Hammerstein Systems with Time-Varying
Nonlinearities
C - Sensory-Motor Interactions
C1 - Faisal Karmali, Koen Lim, Dan Merfeld
Vestibular vs Vision: a comparison of perceptual precision in roll-tilt
C2 - Michael King
Anticipatory eye movements during active head turns
C3 - Alexis Dale, Jerome Carriot and Kathleen Cullen
Neural ensemble coding during self-motion
C4 - Iman Haji Abolhassan, D. Guitton and H.L. Galiana
Head-free gaze shifts: platform coordination without trajectory planning
C5 - Mina Ranjbaran & H.L. Galiana
Modelling the VOR with bilateral non-linear cells for context dependence
C6 - Prem Jareonsettasin, Dale C. Roberts, David S. Zee
Vestibular secondary nystagmus: a reappraisal of short-term vestibular adaptation
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Posters - continued
D - The Vestibular System
D1 - Anna Lysakowski
New discoveries in the vestibular periphery
D2 - Jerome Carriot, Kathleen Cullen
Selective encoding of unexpected head tilt by the vestibular nuclei.
D3 - Mohsen Jamali , Jerome Carriot, and Kathleen E Cullen
Information Processing in the Otolith System
D4 - Diana E Mitchell, Charles C della Santina, Kathleen Cullen
Shaping Central Vestibular Neuron Responses to Prosthetic Stimulation
D5 - Adam Schneider, Kathleen Cullen
Optimal Sensory Coding of Natural Stimulus Statistics in the Peripheral Vestibular System
D6 - Ari Z Zivotofsky,Avi Caspi, Carlos R Gordon
Impaired Vestibular Ocular Reflex (VOR) in presymptomatic Spinocerebellar Ataxia Type 3
Abstracts: Index in order of presentations:
Page
Podium Session I: Learning, Adaptation & Compensation (SAT) 8:30-10:15
6
(SAT) 10:45-12:30
9
(SUN) 9:00-10:45
11
(SUN) 11:15-13:00
14
POSTER Abstracts
(SAT & SUN) PM
17
19
23
26
LIST of Attendees & Affiliations :
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Podium Session I: Learning, Adaptation & Compensation
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Authors: Melvill Jones G , Fletcher WA , Block EW , Galiana HL ,Horak F
Title: Adaptive Interactions Between Podokinetic and Vestibular Systems During Curved Locomotion
Abstract: When a subject, with eyes open, steps in place (i.e. without turning re space) over the centre of a horizontally rotating
turntable for e.g. 30 min, s/he acquires an after effect we term Podokinetic After Rotation (PKAR). This is manifest as an
unperceived directional bias of body angular velocity re space when the now blindfolded subject attempts to continue stepping in
place after cessation of platform rotation. The effect subsequently decays with a time constant (τ) ~ 7 min. We asked what effect
PKAR would have on the ability of a blindfolded subject to walk continuously round a previously seen circle of radius 1m? First we
asked how well and for how long a normal, un-adapted, subject can do so? Surprisingly two individuals succeeded in remaining
close to the intended circle for at least 6 min. Next, one subject attempted the same task after installing PKAR at a conditioning
turntable velocity of 60 deg/sec. His trajectory radius first rapidly reduced from ~ 1 m to ~ 0.5 m with τ ~15 sec, and then slowly
increased towards its original value with τ ~ 7 min. These findings are discussed in terms of known PKAR and vestibular dynamics.
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Affiliations: Dept of Clinical Neurosciences & Hotchkiss Brain Institute, University of Calgary, Canada; Biomedical
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Engineering Dept, McGill University, Montreal, Canada; Dept of Neurology, Oregon Health & Sciences University, Portland, USA.
Authors: Serge Rossignol, M. Martinez and O. Alluin
Title: Spinal plasticity studied after spinal lesions
Abstract: After a complete spinal cord injury (SCI) at a low thoracic level in cats, rats and mice hindlimb locomotion can be reexpressed by a spinal locomotor circuitry (SLC) at lumbo-sacral levels. This SLC can be triggered and tuned by sensory inputs from
the limbs as well as by neurotransmitters. Recent observations using a dual spinal lesion paradigm show that the SLC also plays a
crucial after partial SCI (hemisection). Indeed, after a second and complete spinalization 2-3 segments following the hemisection,
cats can re-express locomotion within 24 hours. This implies that, after hemisection, the SLC was changed to become largely
autonomous and was already in an operative mode after the second transection. Furthermore, this recovery could be improved
by locomotor training between the two lesions. We conclude that after partial spinal lesions the intrinsic plastic changes of the
cord have to be taken into account as major contributors in the recovery of hindlimb locomotion in quadrupeds and that any
treatment or procedures must take into account these important plastic changes that may also occur in humans after SCI.
Affiliations: Groupe de Recherche sur le Système Nerveux Central (FRSQ), SensoriMotor Rehabilitation Research Team
(CIHR), Canada Research Chair on the Spinal Cord (CIHR),Faculty of Medicine, Université de Montréal, Quebec, Canada
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Author: Christina Hui-Chan
Title:
Maximizing neural plasticity: Combing peripheral stimulation with central command to enhance motor recovery in
stroke
Abstract: Human and animal studies have shown that repetitive peripheral electrical stimulation (ES) and voluntary limb
movements could increase excitability of corticospinal projection to, and cortical representation area of, the stimulated muscles.
Furthermore, sensori-motor experience after brain injuries contributes significantly to subsequent cortical reorganisation of
adjacent, intact brain tissues. Will combining peripheral ES with central command enhance motor recovery in stroke?
Using randomized, placebo-controlled trials in patients with chronic stroke, we compared the effectiveness of 4-weeks
of TES alone and in combination with task-related-training (TES+TRT). Interestingly, even 4 weeks after treatment ended, the
TES+TRT group still had significantly increased gait velocity and walking endurance than the other 3 groups receiving TES,
placebo+TRT, or standard rehabilitation alone (control). We then compared the effectiveness of a mind-over-body exercise (Tai
Chi), versus a more body-focused general conditioning exercise (GCE) on balance performance. After 12-weeks, patients
practicing TC performed significantly better in the Limit of Stability Test requiring them to shift their body to different spatial
targets, than those receiving GCE. Such gains even outlasted training for 6 weeks. Conclusion: Findings from two different
approaches demonstrate that combining peripheral stimulation with central command can enhance motor recovery in stroke
patients, probably through augmented neural plasticity.
1
Affiliations: Department of Physical Therapy, University of Illinois at Chicago
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Authors: C.R. Gordon , Y. Manor , A. Stamper
Title: A new approach to prevent backward falls due to imbalance
Abstract: Background: A protective postural response with the execution of a compensatory “extra step” is commonly applied by
physical therapists in neurological patients and elderly persons in order to regain balance and prevent falls. Very often, this
response is too slow and subjects do not success to make the step before falling. A "Balancing shoe" (BS) prototype with an
embedded electro mechanic mechanism has been recently designed in an attempt to replace the extra step by providing the
needed foot displacement to regain balance.
Methods: We tested healthy elderly subjects standing on a computerized platform under two provoking postural instability
conditions: 1) Sudden and brisk forward movement of the platform; 2) Pulling subject backward. Postural reactions were
measured by pressure sensors of the computerized platform and by cameras detecting the displacement of markers mounted
over the subject's body. Results: In most trials, when platform or pull perturbations were enough to produce significant
imbalance, BS rolled back preventing backward falls. In some cases, BS operated concomitantly with the subject who was doing a
step backward. In these cases, subject and BS "worked together" and complemented each other.
Conclusions: BS seems to be a feasible mean for preventing backward falls.
1
Afffiliations: Department of Neurology, Meir Medical Center, Kfar Saba and Sackler Faculty of Medicine, Tel Aviv
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University, Tel Aviv; B-Shoe Technologies Ltd; Haifa, Israel - Supported by a fund of The Ministry of Industry, Trade and Labor,
Office of the Chief Scientist, Technological Incubators Program, Israel. YM and AS are co-founders of B-Shoe technologies.
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3,*,
1,*
Author(s): F.M. Lambert , D. Malinvaud , M. Gratacap , H. Straka # and P.P. Vidal
Title:
“Une histoire de grenouille tordue” – The twisted frog story
Abstract: Adolescent idiopathic scoliosis in humans is often associated with vestibulo-motor deficits. Compatible with a vestibular
origin, scoliotic deformations were provoked in adult Xenopus frogs by unilateral labyrinthectomy (UL) at larval stages. We
hypothesize that the induction of skeletal deformations after UL depends on a manifested asymmetric activity in descending
vestibulo-spinal pathways in the absence of body weight-supporting limb proprioception. To test this hypothesis, we examined
the causality between morpho-physiolocial alterations at cellular and network levels and the peripheral vestibular lesion in larval
Xenopus. As a result, spinal motor nerves that were modulated by the previously intact side before UL remained silent during
natural vestibular stimulation after the lesion. In addition, retrograde tracing of hindbrain descending pathways revealed a
significant neuronal loss of ipsilesional crossed vestibulo-spinal projections. This loss facilitates a general mass imbalance in
descending premotor activity and a permanent asymmetric motor drive to the axial musculature. Consequently, we propose that
the persistent asymmetric contraction of trunk muscles exerts a constant, uncompensated differential mechanical pull on
bilateral skeletal elements, which enforces a distortion of the soft cartilaginous skeletal element and bone shapes. This finally
provokes severe scoliotic deformations during the ontogenetic development similar to the human syndrome.
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Affiliation(s): CeSeM, CNRS UMR 8194, Université Paris Descartes, 45, rue des Saints-Pères, 75006 Paris, France;
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Département d’ORL et de Chirurgie Cervico-Faciale, Hôpital Européen Georges Pompidou, 20 rue Leblanc, 75015 Paris, France;
Department Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstr. 2, 82152 Planegg, Germany* H.S. and P.P.V.
contributed equally to this work.
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Authors: Fay Horak , Adam Goodworth , Martina Mancini , Carolyn Paquette , Edward W. Block , William A. Fletcher and
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Geoffrey Melvill Jones
Title: Turning is more difficult than walking straight
Abstract: Neural control of turning requires the complex coordination of forward locomotor progression with angular control of
feet and trunk motion. We hypothesized that the nervous system exerts different type of control of linear and angular motion
during curvilinear locomotion and that cerebellum and basal ganglia are involved in control of angular locomotion. Patients with
anterior lobe cerebellar ataxia and age-matched control subjects walking around a 1.2 meter circle with eyes open. All subjects
showed large coefficients of variation in angular, compared to linear, motion of the feet and trunk. Angular, but not linear, control
of foot motion involved stride-by-stride corrections of foot trajectory. Errors in walking radius (ratio of linear to angular motion)
were significantly increased and variability of angular, but no linear motion, in patients with cerebellar degeneration compared to
controls. Recently, we also developed a novel algorithm to capture walking and turning events during unconstrained,
spontaneous activities with body-worn inertial sensors. We found that older people make over 500 turns per day. The variability
of number of turns per hour and variability of turning amplitude over a week are related to fall risk, working memory and
Parkinson’s disease. Turning may require a higher level of active neural control than walking.
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Affiliations: Oregon Health and Science University, Dept. of Neurology, Portland; University of Hartford , Dept. of
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Physical Therapy and Center for Health, West Hartford, CT; McGill University at SMBD-Jewish General Hospital & Lady Davis
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Institute Department of Neurology & Neurosurgery, Montreal, Quebec, CAN; University of Calgary, Dept. of Clinical
Neurosciences, Calgary, Alberta, CAN.
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Author: Gammon M. Earhart
Title: Turning Point: How Experience Can Modify Trajectory
Abstract: The experience of walking in place on a rotating surface results in an adaptive after-effect during which trajectory is
modified in such a way that individuals asked to walk in a straight line without vision following exposure to the rotating surface
will instead unknowingly turn in circles. This after-effect was discovered and first described by Geoffrey Melvill Jones and
colleagues, who called the response podokinetic after-rotation (PKAR). Since the first description of this phenomenon in the mid
1990’s, numerous studies used PKAR as a probe to examine how locomotor experience modifies trajectory. These studies noted
the robustness of the PKAR response, its transfer across different tasks, how it is affected by different sensory inputs and the role
of different nervous system structures in mediation of PKAR. This talk will synthesize these studies, culminating in the
presentation of a working model illustrating how experience can modify trajectory, and will highlight how my experiences
studying PKAR with Geoffrey Melvill Jones positively modified my own trajectory.
1
Affiliations: Program in Physical Therapy, Department of Neurology, Department of Anatomy and Neurobiology,
Washington University in St. Louis School of Medicine, St. Louis, MO USA
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Authors: Caroline Paquette , Jean-Paul Soucy , Erika Franzén , Anouk Lamontagne , Fay Horak and Geoffrey Melvill Jones
Title: Steering gait mechanisms in the human brain
Abstract: Walking is one of the more frequently performed sensorimotor tasks in everyday life relying on a complex,
simultaneous interaction of the motor system, sensory control, and cognitive functions. We have previously shown that more
complex locomotor tasks such as turning while walking, in contrast to straight walking, results in movement pattern abnormalities
in the healthy elderly, subjects with cerebellar ataxia, Parkinson’s disease and stroke. Our findings thus suggest that the control of
steering and straight walking might be controlled by different neuronal structures. Currently little is known on how brain
networks conveying “volitional” mobility goals (steering of gait) interact with the more “automatic” rhythmic pattern outputs
(straight walking), mostly due to the difficulty in quantifying brain activations during whole body movements. The only metric
available to measure whole-brain activations during gait is with 18F- fluorodesoxy-glucose (18F-FDG) Positron Emission
Tomography (PET). We have recently implemented this technique to reveal brain activations related to steering of locomotion in
healthy and stroke subjects therefore allowing us to determine how subcortical infarcts affect global neuronal networks involved
in the control of steering.
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Affiliations: Kinesiology & Physical Education and Neurology & Neurosurgery, McGill University, CAN; Centre for
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Interdisciplinary Research in Rehabilitation of Greater Montreal, CAN; Brain Imaging Centre, McGill University, CAN;
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Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, SWE; Physical and Occupational Therapy, McGill
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University, CAN; Oregon Health and Science University, Dept. of Neurology, Portland, OR, USA; 7. University of Calgary, Dept. of
Clinical Neurosciences, Calgary, Alberta, Canada
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Authors: Robert E Kearney , Kian Jalaleddini , Diego Guarin , and Ehsan Sobhani ,
Title: New Methods For Estimating Joint Stiffness During Posture And Locomotion
Abstract: Joint stiffness describes the dynamic relation between the position of a joint and the torque acting about it. Thus,
quantitative, dynamic knowledge of joint stiffness and the relative contributions of reflex and intrinsic mechanism to it are
essential to understand how the CNS controls posture and movement. There is now a good understanding of how joint stiffness
behaves under well-controlled experimental situations where the operating point (e.g. mean joint position and muscle activation
level) is stationary. These results demonstrate that joint stiffness is highly nonlinear, varies greatly with the operating point, and
may be time-varying. Thus, estimating joint stiffness during functional activites will require specialized methods to deal with the
nonlinear, time-varying behavior evoked by rapid changes in operating point. They must also account for the feedback connection
between position and torque which prevails during unconstrained movements. This talk will first discuss that nature and
importance of these problems for system identification.The general nature of the issues will be demonstrated by reference to the
system identification work of Melvill Jones. It will then describe some new system identification tools, under development in my
laboratory, to address these problems with special reference to joint stiffness.
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Affiliations: Post Doctoral Fellow (1976-77), Aviation Medical Research Unit, McGill University:
2
Department of Biomedical Engineering, McGill University
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Author: Laurence R. Young
Title: Models for Adaptation of the VOR
Abstract: Interest in adaptation of the vestibulo-ocular “reflex” was heightened enormously when Gonshor and Melvill Jones
published their prism adaptation paper (Extreme vestibulo-ocular adaptation induced by prolonged optical reversal of vision) in
1976. Ito, Robinson, and others had speculated about the extent such an elementary reflex could adapt to meet the needs of the
environment – but here was an undeniable and dramatic example. It led to a cottage industry of magnifying, minifying, rotating
and distorting visual fields – with neurophysiological correlates. Many of us including Henn, Cohen, Malcolm, Miles, Lisberger,
Oman and myself quickly brought adaptive control models to bear on the phenomenon. Mathematical models have played an
important role in research on the vestibular system over the past century, from the torsion pendulum analogies to models of
multisensory interaction and adaptation. This talk is limited to our own contributions with the technology of feedback control
theory to understand human spatial orientation, eye movements, and nystagmus, both on Earth and in space. It points to the
importance of the ‘‘internal model’’ concept as a mechanism to explain how the brain constantly makes predictions about future
sensory feedback, adjusts the weightings of sensors according to their signal-to-noise ratios, and adapts control according to the
motion environment, and availability of sensory cues. (Ref. Young, L.R. Optimal estimator models for spatial orientation and
vestibular nystagmus; Exp Brain Res (2011) 210:465–476)
Affiliation: 1 Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, USA;
Supported by MIT/Skoltech
1,
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Authors: R. John Leigh Rosalyn Schneider Ke Liao Mark F. Walker Adolfo Bronstein
Title: Human Translational VOR during Combined Rotations and Translations
Abstract: Inspired by a conversation with Geoffrey Melvill Jones at a Society for Neuroscience meeting, we set out to address a
paradox: During pure head translations, vestibular eye movements are typically only 60% of those required to hold the foveal line
of sight on target but, during rotation of the head about an eccentric axis, which causes translation of the orbits, vestibular eye
movements do hold the eye on target. We measured eye and head rotations and translations as subjects sat on a moving
platform viewing a near target and were: (1) rotated en bloc in yaw about a vertical axis centered on the head at 1 Hz; (2) rotated
with their head displaced ~10 cm anterior (eccentric rotation) at 1 Hz; (3) translated along the inter-aural axis at 1.9 Hz; (4)
rotated with the head centered at 1 Hz while they were translated along the inter-aural axis at 1.9 Hz. We calculated
compensation ratio (CR): Eye velocity/eye velocity geometrically required to hold the eye on target. During yaw mean CR was 0.88
and during eccentric rotation CR was 0.93. During translation at 1.9 Hz, CR was 0.65. During combined rotation at 1.0 Hz and
translation at 1.9 Hz, CR was 0.81 for head rotations and 0.74 for head translations. We conclude that translations of the orbits
due to head rotation are better compensated for than translations of the orbits due to head translation. These different behaviors
may be determined by context, the important difference being whether the subject is moving through the environment or
rotating in place.
1
Affiliations: Department of Veterans Affairs Medical Center and Case Western Reserve University, Cleveland Ohio
2
44106 USA; Neuro-Otology Unit, Division of Experimental Medicine, Imperial College London, Charing Cross Hospital, London, UK
Correspondence to: R. John Leigh, M.D. rjl4@case.edu
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Author(s): Zee, DS , Roberts, DA , Ward, B , Jareonsettasin, P , Della Santina, C , Carey, J
Title: Effects of the Magnetic Field of Strong MRI Machines on the Brain
Abstract: We have shown that all normal human subjects who lie in a 7T MRI machine develop a sustained nystagmus that is
independent of taking any images (Roberts et al. Current Biology, 2011). The intensity and direction of the nystagmus depends on
the static orientation of the head in pitch and all subjects show a null. Studies in both intact subjects and patients with unilateral
or bilateral vestibular loss, support the hypothesis that the nystagmus results from a static magneto-hydrodynamic force (Lorentz
force) which develops from the interaction between the magnetic field and the ionic currents in the endolymph which in turn
produces a pressure that pushes on the cupula. We show also that such a mechanism accounts for nystagmus in mice and the
abnormal swimming behavior of Zebra fish that are placed in an MRI machine. We also show that the nystagmus induced by the
magnetic field can be used to study the short-term (minutes) adaptive mechanisms that can null an unwanted sustained
nystagmus. We discuss the possible implications of MRI induced nystagmus on functional imaging studies, including resting state
MRI, the anatomical organization of central vestibular projection, and the anatomical substrate of vestibular adaptation.
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Affiliations: Department of Neurology and Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins
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Hospital, Baltimore, MD, USA, and Cambridge University, Cambridge, England
Author: Henrietta L. Galiana
Title: Reaching with the eye and reaching with the hand: Common Principles?
Abstract: Historically, it has been assumed that control of rotary platforms such as the eyes in the head is quite distinct from the
control of segments in a limb. Namely, the former are accepted as being ballistic, especially during saccades, and otherwise rely
on short latency reflexes like the VOR; instead limb control is presumed to require complex trajectory planning before movement
is released. Yet there is evidence that several brain structures are shared by both eye and limb control signals; for example signals
related to gaze control and reaching errors can be found in the superior colliculus. This talk will illustrate how the same basic
strategies could be used in movement control at all levels, without explicit pre-planning. These are: 1) A map structure for goal
errors, 2) non-linear gain fields projecting a global error simultaneously to all muscle platforms participating in the task, 3)
feedback of all platform contributions to the map reducing the error. In this view, spatio-temporal dynamics emerge from
controller loop gains, not preplanning, and local reflexes restore trajectories during perturbations without explicit computation
for path correction. Simple examples from simulations of horizontal gaze shifts and 2D hand reaches will be provided.
Affiliation: Department of Biomedical Engineering, Faculty of Medicine, McGill University
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Authors: Mathieu Boulanger , Henrietta L. Galiana , and Daniel Guitton
Title: Human eye-head gaze shifts preserve accuracy and spatiotemporal trajectory profiles
despite long-duration torque
perturbations that assist or oppose head motion
Abstract: Classic engineering tools have investigated the structure of motor systems by testing their ability to compensate for
perturbations. When a reaching movement of the hand is subjected to an unexpected force field of random direction and
strength, the trajectory is deviated and its final position is inaccurate. Here, we found that the gaze (eye + head) control system
behaves differently. During horizontal gaze shifts we applied long-duration torques to the head that unpredictably either assisted
or opposed head motion and very significantly altered the intended head trajectory. We found, as others have with brief head
perturbations, that gaze accuracy was preserved. Unexpectedly, for long duration head perturbations we found that the eye
compensated such that resulting gaze trajectories remained close to that when the head was not perturbed. The ocular
compensation was best when torques assisted, compared to opposed, head motion; in the former condition, in some subjects the
whole gaze trajectory occurred while the eye rolled backwards in the orbit. If the VOR is suppressed during gaze shifts, as
currently thought, what caused invariant gaze trajectories and accuracy, early eye-direction reversals and asymmetric
compensations? An answer is proposed in our associated poster.
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Affiliations: Montreal Neurological Institute, McGill University, Montreal; Department of Biomedical Engineering,
McGill University, Montreal
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Author: Kathleen Cullen
Title: The neural encoding of vestibular information during natural self-motion
Abstract: Understanding how sensory pathways transmit information to ensure accurate perception and motor control is a major
goal in neuroscience. We have recently made progress towards understanding how the brain encodes and processes vestibular
information during every day life. First, by taking advantage of modern computational tools we found that i) regularly firing
afferents have higher information rates and lower detection thresholds than irregular afferents, and ii) regular afferents transmit
sensory information with a spike-timing code, while irregular firing irregular afferents use a rate code. Furthermore, our recent
findings overturn common wisdom that vestibular pathways use a linear rate code to transmit information. Specifically, we have
shown that nonlinear integration of afferent input extends the coding range of central vestibular neurons, enabling them to
preferentially extract the high frequency features of self-motion. We speculate that this selectivity optimizes our ability to
reflexively respond to unexpected transient events in everyday life. Finally, we have demonstrated that under natural conditions,
behavioral context governs how vestibular is encoded at the first central stage of processing. Not only is vestibular (self-motion)
processing inherently multimodal, but the manner in which multiple inputs are combined is adjusted to meet the needs of the
current behavioral goal.
Affiliation: Department of Physiology, McGill University
Author: Ruth Anne Eatock
Title: The impact of low-voltage-activated potassium channels on signaling by type I hair cells and calyceal afferents
Abstract: Low-voltage-activated potassium (KLV) channels are activated at resting membrane potential, making resting potentials
more negative and reducing membrane resistance and charging time. Such channels come from multiple K channel families,
including Kv1, Kv7, and Kv11, and in such neuronal systems as the auditory timing pathway are believed to contribute importantly
to the speed of voltage signaling. One of the most striking features of type I hair cells in vestibular epithelia is their expression of
large numbers of KLV channels. Acquisition of these channels with maturation substantially broadens frequency tuning and
reduces phase lag (response latency) at high stimulus frequencies (>10 Hz). The type I hair cells are closely apposed to calyceal
afferent terminals which also bear large numbers of KLV channels, particularly in the striolar zones of maculae and central zones of
cristae, where they improve the speed of afferent voltage signals and at the same time contribute to the irregularity of spike
timing. The intense expression of KLV channels complements other specializations of central and striolar zones for speed.
Afffiliation: Dept. Otology & Laryngology and Neurobiology, Harvard Medical School
Page 14
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Author(s): Dan Merfeld , Yulia Valko , Adrian Priesol , and Rick Lewis
Title: Subjective Detection of Vertical Acceleration: A Velocity Dependent Response?
Abstract: The title of this talk mimics the title of a 1978 Melvill Jones paper. We have recently reinvestigated this question using
forced choice procedures and signal detection analyses to estimate human thresholds as a function of frequency between 0.1 and
5 Hz. We used a direction recognition task in which subjects were instructed to report their perceived motion direction. We
found that the thresholds we measured for yaw rotation, inferior-superior vertical translation, and inter-aural horizontal
translation suggested a constant-velocity threshold plateau at higher frequencies. But thresholds increase substantially as
frequency decreased below 1 Hz. This frequency response is consistent with high-pass filtered velocity being the canonical
amplitude variable determining these thresholds. The phasic nature demonstrated by the high-pass nature of the neural
processing is consistent with phasic aspects of locus coeruleus neurons known to contribute to decision making. We conclude
that direction recognition thresholds support the conclusion drawn back in the 1978 paper by Melvell Jones and Young. Further,
by measuring responses in select vestibular patients, we show that the vestibular system is the predominant contributor to these
threshold responses.
1
Affiliations: Jenks Vestibular Physiology Laboratory, Mass. Eye and Ear Infirmary;
2
3
Otology and Laryngology, Harvard Medical School and Neurology, Harvard Medical School
1,2,3
1
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2
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1,2
Authors: Richard Lewis , Csilla Haburcakova , Wangsong Gong , Daniel Lee , Keyvan Nicoucar , Daniel Merfeld
Title: Central vestibular processing investigated with electrical stimulation of semicircular canal afferents
Abstract: We have studied the effects of electrical stimulation of semicircular canal afferents in several animal models to
investigate central vestibular processing and to obtain information that is necessary for the development of a canal prosthesis.
This talk focuses on the scientific observations we have made using this technique, and includes discussion of:
1) Vestibular compensation to a static tone imbalance when it is introduced at different rates or repeatedly cycled on and off.
2) Velocity storage and an apparent dissociation between its gravity-dependent features and its effects on the low frequency
vestibulo-ocular reflex (VOR).
3) Evidence that the brain estimates head orientation relative to gravity by integrating semicircular canal inputs.
4) Evidence that the brain generates a linear VOR response when the estimated orientation of the head relative to gravity is
dissociated from its actual orientation
5) Evidence that adding noise to canal afferents using very high frequency electrical stimulation increases the leakiness of the
velocity storage integrator.
1
2
Affiliations: Jenks Vestibular Physiology Laboratory, Massachusetts Eye and Ear Infirmary; Department of Otology &
3
Laryngology, Harvard Medical School Department of Neurology, Harvard Medical School
Page 15
1
Author: Jay M. Goldberg
Title: Cellular Basis of Discharge Regularity in the Vestibular Nerve and Its Impact on Encoding
Efficiency
Abstract: Vestibular-nerve afferents that differ in discharge regularity also differ in several other discharge properties, as well as
in the morphology of their peripheral terminations. Intra-axonal recordings in the turtle posterior crista coupled with an
integrate-and –fire model have clarified the role of subthreshold events in determining regularity. As compared to irregular units,
regular units have deeper, slower AHPs and smaller mEPSPs that occur at much higher rates. These differences reproduce the
discharge regularities across the afferent spectrum and result in depolarization sensitivities being low in regular units and high in
irregular units. The latter units have more phasic response dynamics than regular units; as a result the gains of irregular units
increase as stimulation frequency is raised, whereas the gains of regular units remain almost constant. Mutual information
calculations indicate that regular and irregular units are optimized in the encoding of low- and high-frequency rotations,
respectively. The superior ability of irregular units to encode higher frequencies depends on their phasic response dynamics
leading to a frequency-dependent gain enhancement. This functional requirement rationalizes the nearly universal association of
discharge regularity and response dynamics even though these two discharge properties are not causally related.
1
Affiliation: Department of Pharmacological & Physiological Sciences, University of Chicago, Chicago, IL USA
Page 16
POSTER Abstracts
A1 - Author: Yoshiro Wada
Title: Changes in head tilt perception and ocular counter-rolling under both microgravity and hypergravity induced by parabolic
flight
Abstract: Head tilt perception relative to the trunk (HTP) and ocular counter-rolling (OCR) were examined under static leftward or
rightward head roll-tilt (approximately 20 degrees) conditions with or without visual information during two separate sessions: on
the ground (1G) and during parabolic flights (micro-G and hyper-G) in normal male subjects (n=4). Compared to baseline data in 1
G without visual information, in micro-G, HTP declined but still functioned especially in two subjects who overestimated it in 1 G,
whereas OCR decreased to near zero in all subjects. In hyper-G, HTP increased/decreased in subjects who overestimated
/underestimated it in 1 G, but OCR remained almost unchanged in all subjects. HTP was affected by visual information in 1 G and
hyper-G, but not in micro-G. OCR was little affected by visual information in micro-G, 1 G and hyper-G. These data suggested that
HTP can be generated by signals from neck proprioceptors and/or central nervous system without otolith and visual information
during a short-term (20 sec) exposure of micro-G, but not OCR. As horizontal optokinetic nystagmus and after-nystagmus were
measured on the ground in the same subjects in an additional experiment, we discuss the effect of velocity storage system on
these results.
Affiliation: Department of Physiology, Nara Medical University, Kashihara 634-8521, Japan
1,2
3
2
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4
A2 - Authors: Mark Shelhamer , Aaron Wong , Kara Beaton , Michael Schubert , Stephen Lowen
Title: Predicting Sensorimotor Adaptation Ability through Fractal Time Series Analysis
Abstract: Humans exhibit remarkable adaptive capabilities, although not all subjects are equally adaptable. The ability to forecast
adaptive capability would be extremely useful in designing programs of rehabilitation and training. We can make such forecasts.
For saccades, subjects generated a sequence of predictive saccades. Correlations between consecutive amplitudes decays
gradually, reflecting error storage and processing. The strength of these correlations is strongly associated with rate of adaptation
in a subsequent double-step paradigm; both tasks require storage of error information for generation of subsequent movements.
In the VOR, subjects performed a sequence of head position steps; gain was found for each. Subjects then underwent 20 minutes
of adaptation with sinusoidal head movements and 0.5x lenses. Inter-trial correlations in the first task were strongly associated
with adaptive change in the second task. This relationship, however, is opposite to that for saccades. For the VOR, weaker intertrial correlations are associated with better adaptation. This difference between systems is because movement error is only
available at the end of a saccade and hence must be stored to affect subsequent saccades, while retinal-slip error is constantly
available in the VOR in real time and storage of error information is detrimental because it provides outdated information.
1
Affiliations: Department of Otolaryngology – Head & Neck Surgery, Johns Hopkins University School of Medicine;
2
3
Department of Biomedical Engineering, Johns Hopkins University School of Medicine; Department of Neurology, Johns Hopkins
4
University School of Medicine; Department of Psychiatry, Harvard Medical School.
Page 17
A3 - Authors: Johannes van der Steen, Joyce Dits and Johan Pel
Title: Sensing and memorizing motion for action
Abstract: In daily life visual orientation requires not only that we can update locations of objects in 3D space and remember their
positions when they are temporarily out of sight, but also that we can take into account our own body motion to update the
location of a remembered object. Previous studies have shown that we can indeed control binocular gaze from memory,
steering our direction (version) and distance (vergence) of gaze towards a memorized fixation point. In this study we used
dynamic trials in which we added a rotation or translation during the memory period to study the effect of vestibular information
on the accuracy of the movements of both eyes.. During these dynamic trials, we applied passive Gaussian velocity whole body
yaw rotations (A=10º, Vmax=33º/s) or translations (A=10cm, Vmax=0.3m/s) produced with a 6DF motion platform. Six subjects
were instructed to fixate a platform-fixed visual target in front of the left eye, either at 94cm (“far”) or at 31cm (“near”) in depth.
A space-fixed target, left or right of the platform-fixed target sight line at 45cm viewing depth, was flashed 80ms before platform
motion onset. During randomized “near” or “far” fixation trials subjects were asked to make a saccade to the remembered
locations of the space-fixed target after the platform-fixed target was dimmed. Memory-guided eye movements in depth were
more accurate when divergence was required than for convergence. Vergence inaccuracies were mainly due to gaze errors in the
adducting eye. Spatial update performance was significantly better for rotations than for translations.
Affiliation (All authors): Erasmus University Medical Center, Dept. Neuroscience, Rotterdam, The Netherlands
A4 - Authors: B. Winkelman, T. Belton, M. Suh, M. Coesmans, M. Morpurgo, and J. Simpson
Title: Floccular Complex Spikes: Their Light and Dark Sides
Abstract: The complex spike (CS) activity of Purkinje cells of the cerebellar flocculus is well-known to be modulated by retinal
image motion. In addition, non-visual CS modulation also occurs, as revealed during rotation in darkness. The visual CS response
is well-characterized and features prominently in cerebellar motor learning models of vestibulo-ocular reflex adaptation. The nonvisual CS response, transmitted by the same climbing fibers that mediate the visual CS response, has, however, received scant
attention. To form a more complete picture of the signals carried by floccular climbing fibers, we quantitatively characterized the
frequency and velocity dependence of the non-visual CS modulation. Recordings from alert rabbits showed that about 75% of the
visual climbing fibers also carry non-visual signals. The non-visual CS modulation apparently reflects competition between eye
movement and vestibular signals, resulting in an inferred error signal. Combination of the visual and non-visual error signals in the
inferior olivary results in a net error signal reporting the discrepancy between the visually measured eye movement error and the
inferred eye movement error. The presence of two eye movement error signals requires that the role of CSs in models of the
floccular control of eye movement adaptation be expanded beyond retinal slip.
Affiliation (All authors): Physiology & Neuroscience, NYU Medical Center, New York, NY 10044
Page 18
A5 - Author: Donna Mergler
Title: Neurophysiology applied to epidemiologic studies of environmental toxics: mercury and
manganese
Abstract: Many environmental and occupational pollutants have neurotoxic properties, which, even at doses insufficient to cause
clinical neurologic damage, can alter motor, sensory and cognitive functions. Identification of early neurotoxic changes in
epidemiologic studies can lead to prevention of further damage or even reversibility. High exposure to mercury, a worldwide
contaminant, bioaccumulated in the aquatic food chain, is known to cause Minamata Disease. Our research on motor and visual
dysfunction among fish-eating communities in the Brazilian Amazon lead to strategies for maximizing nutritional intake from fish
while minimizing toxic risk. A different challenge is posed by manganese, an essential element, which, in excess, is neurotoxic.
Manganism, a neurologic disorder, with Parkinson-like signs and symptoms, has been extensively described in miners, industrial
workers and welders. Our recent studies in Quebec reveal that manganese in well water, at concentrations below the World
Health Organization recommendations, is associated with poorer intellectual capacities in children. In Costa Rica, we are
currently following up a birth cohort of mother-child pairs exposed to manganese through pesticide spraying. Preliminary results
of testing at one year of age suggest reduced cognitive function associated to elevated manganese during pregnancy.
Affiliation: Professor Emerita, Université du Québec à Montréal (UQAM), Quebec, Canada
1
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B1 - Authors: Block EW , Fletcher WA , Horak F , Goodworth A and Melvill Jones G ,
Title: Curvature of the Locomotor Trajectory is controlled by the Ratio of Angular to Linear Components of Podokinetic Nystagmus
– A review
Abstract: What is “Podokinetic Nystagmus” ? We define it as the pattern of both linear and angular components of limb
movement responsible for controlling the curvature of a locomotor trajectory. Analogous with ocular nystagmus, there are both
compensatory and saccadic phases in each of these components. During stance the locomotor system drives the trunk forward
and round along the track, at corresponding linear (V) and angular (Ω) velocities; notably in such a way that the ratio (V/ Ω )
1
ideally equates to track radius (R) . We term these the compensatory phases: i.e. movement of the stance foot re trunk
compensates respectively for linear and angular components of trunk movement re space. During swing the foot is quickly thrust
both forward (stride length L) and round (stride angle Ө) to the next stance position; notably in such a manner that the ratio (L/
Ө) ideally equates to R. We term these the saccadic phases: i.e. there is rapid linear and angular relocation of the stance foot to a
new space stable position on the track from which to conduct the next compensatory phases. In the adjacent poster we examine
temporal relations between the linear and angular components of podokinetic nystagmus.
1. Exp. Brain Res. 219: 151-161 (2012)
1
2
Affiliations: Dept of Clinical Neurosciences & Hotchkiss Brain Institute, University of Calgary, Canada; Dept of Neurology,
3
Oregon Health and Sciences University, Portland, Oregon, USA; Dept of Physical Therapy, Center for Health, Care and WellBeing, University of Hartford, Connecticut, USA
.
Page 19
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B2 - Authors: Block EW , Fletcher WA , Horak F ,Melvill Jones G ,
Title: Synchrony of Linear and Angular Components of Podokinetic Nystagmus During Curved Locomotion
1
Abstract: In the early 1970s GMJ & DW showed that anticipatory, rather than reflex, motor action permits a smooth landing
from a vertical step to the ground. The question arises whether a similar anticipatory strategy applies to the linear and angular
components of swing foot landing during bipedal locomotion round a curved trajectory. In a preliminary study two subjects
walked round a visible circle of 1 m radius while an in-house inertia-sensing system separately recorded (at 200 Hz) linear and
angular movements of trunk and one foot relative to space and to the moment of touch-down throughout a sequence of cycles
of the resulting podokinetic nystagumus (see adjacent poster). Original nystagmoid traces are shown of linear and angular
components of movement for 1. foot-re-space, 2. trunk-re-space, 3.foot-re-trunk and 4. moment of landing. Superposition of
linear and angular traces illustrates the degree of synchrony between these orthogonal degrees of freedom of movement.
Preliminary results from two subjects suggest a strong tendency for spatial stabilization just before touch-down and for tight
temporal synchrony between linear and angular components of the cycle.
{ J. Physiol. Lond.. 219: 709-727 (1971) }
1
Affiliations: Dept of Clinical Neurosciences & Hotchkiss Brain Institute, University of Calgary, Canada;
2
Dept of Neurology, Oregon Health and Sciences University, Portland, Oregon, USA
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B3 - Author(s): Marina Martinez , Eléonore Serrano , Paul Xing , Hugo Delivet-Mongrain , Serge Rossignol
Title: Role of dorsolateral pathways in locomotor recovery after spinal hemisection in cats
Abstract: After a thoracic hemisection disrupting unilaterally the sensorimotor tracts, cats can recover a voluntary control of the
affected hindlimb within 3 weeks. Such a recovery is paralleled by sublesional spinal changes and reorganization within residual
descending pathways known to be involved in the voluntary control of hindlimb locomotion such as cortico- and rubrospinal
tracts that travel within the dorsolateral funiculus (DLF). Herein, we raise the question of whether the residual DLF pathways
participate the recovery of the hindlimb affected by a hemisection. Four cats were submitted to a hemisection on the left side at
T10 level and were allowed to recover for 3-4 weeks. Thereafter, the right DLF was lesioned at the same spinal level. Unskilled
and skilled locomotion was evaluated on a treadmill, on a horizontal ladder and overground in the intact state and then for 6-7
weeks after hemisection. We showed that completely disrupting the residual DLF pathways abolished the voluntary control of the
hindlimb that had recovered from a hemisection for 2-3 weeks while a partial lesion of these tracts did not. These results show
that remnant pathway from motor cortex and red nucleus play a key role in the voluntary recovery of hindlimb locomotion after
hemisection.
1
Affiliation: Groupe de Recherche sur le Système Nerveux Central (FRSQ), Université de Montréal, Department of Physiology,
2
Montreal, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute for Health Research.
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B4 - Authors: Stephanie Haggerty , Amy Wu , Arthur Kuo , Kathleen H. Sienko
Title: Effects of Optokinetic and Galvanic Vestibular Stimulation on Standing Posture
Abstract: Gaze can be stabilized by two reflexes: optokinetic, driven by visual information, and vestibular-ocular, driven by
vestibular information. By linking these systems with a single leaky integrator, the velocity storage unit explained how these two
seemingly independent pathways produced complimentary responses with a shared time constant. Borah (1988) extended this
model by including somatosensation and could thus reproduce motion perception data across a variety of spatial orientation
tasks. As standing balance also uses these sensory inputs we tested whether a central estimator can similarly describe postural
responses. We presented 16 young adults with optokinetic (OK) and galvanic vestibular stimulation (GVS) designed to provoke
analogous sensations of constant angular velocity about the roll axis. Subjects stood in narrow stance and center of pressure
(CoP) was used as a measure of tilt. We found that the effects of OK and GVS on CoP were indeed complementary and, when fit
with exponentials, had similar time constants. These results support the hypothesis that the central estimators previously used to
describe eye movements and motion perception can be extended to postural responses as well. As such, these models could be
used to predict the postural responses of various patient populations allowing for more comprehensive diagnostics.
1
Affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
2
Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
1
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B5 - Author(s): Diego Guarin Lopez , Kian Jalaleddini and R.E. Kearney
Title: Identification of a Parametric, Discrete-time Model of Ankle Stiffness.
Abstract: Dynamic ankle joint stiffness defines the relationship between the position of the ankle and the torque acting about it
and can be separated into intrinsic and reflex components. Under stationary conditions, intrinsic stiffness can described by a
linear second order system while reflex stiffness is described by Hammerstein system whose input is delayed velocity. Given that
reflex and intrinsic torque cannot be measured separately, there has been much interest in the development of system
identification techniques to separate them analytically. To date, most methods have been nonparametric and as a result there is
no direct link between the estimated parameters and those of the stiffness model. This paper presents a novel algorithm for
identification of a discrete-time model of ankle stiffness. Through simulations we show that the algorithm gives unbiased results
even in the presence of large, non-white noise. Application of the method to experimental data demonstrates that it produces
results consistent with previous findings.
1
Affiliations: Dept. Biomedical Engineering, McGill University, 3775 University St, Montreal QC H3A 2B4, Canada
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B6 - Author(s): Seyed Kian Jalaleddini and R.E. Kearney
Title: Subspace Method Decomposition and Identification of the Parallel-cascade Model of Ankle Joint Stiffness: Theory and
Simulation
Abstract: This poster describes a state-space representation of the parallel-cascade model of ankle joint stiffness whose
parameters are directly related to the underlying dynamics of the system. It then proposes a two step subspace method to
identify this model. In the first step, the intrinsic stiffness is estimated using proper orthogonal projections. In the second step,
the reflexive pathway is estimated by iterating between estimating its nonlinear and linear components. The identified models
can be easily converted to continuous-time for physiological interpretation. Monte-Carlo studies using simulated data which
replicate closely the experimental conditions, were used to compare the performance of the new method with the previous
parallel-cascade, and subspace methods. The new method is more robust to noise and is guaranteed to converge.
1
Affiliations: Dept. Biomedical Engineering, McGill University, 3775 University St, Montreal QC H3A 2B4, Canada
B7 - Authors: Ehsan Sobhani Tehrani, Kian Jalaleddini, Robert E. Kearney
Title: A Novel Algorithm for Linear Parameter Varying Identification of Hammerstein Systems with Time-Varying Nonlinearities
Abstract: This paper describes a novel method for the identification of Hammerstein systems with time-varying (TV) static
nonlinearities and time invariant (TI) linear elements. We develop a linear parameter varying (LPV) state-space representation for
such systems and present a subspace identification technique that gives individual estimates of the Hammerstein components.
The identification method is validated using simulated data of a TV model of ankle joint reflex stiffness where the threshold and
gain of the model change as nonlinear functions of an exogenous signal. A pilot experiment of TV reflex identification from EMG
responses in normal a ankle joint during an imposed walking task demonstrate systematic changes in the reflex dynamics
(nonlinearity) with the trajectory of the joint position operating point.
Affiliation: Department of Biomedical Engineering, Faculty of Medicine, McGill University, Montreal, Canada
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C1 - Authors: Faisal Karmali , Koeun Lim , Dan Merfeld
Title: Vestibular vs. vision: a comparison of perceptual precision in roll tilt
Abstract: It is unclear whether vestibular or visual cues provide more precise information about self motion. Some prior work
suggest that vestibular motion perception is less precise than visual motion perception, but this may be the result of specific
experimental conditions. We compared vestibular and visual motion precision by measuring thresholds to vestibular (subject
motion in the dark), visual (visual scene motion) or visual-vestibular (subject motion in the light) stimuli. Thresholds were
measured across a range of frequencies spanning two decades (0.05 Hz to 5 Hz) using single-cycle sinusoidal acceleration
trajectories in roll tilt (i.e. distinguishing left-ear down from right-ear down). We found that each cue is significantly more precise
than the other at certain frequencies. Specifically, we found that: 1) visual and vestibular thresholds were indistinguishable at
0.05 Hz and 2 Hz, 2) visual thresholds were lower (i.e. more precise) than vestibular thresholds between 0.1 Hz and 1 Hz, and 3)
vestibular thresholds were lower (i.e. more precise) than visual thresholds above 2 Hz. Thus, in contrast to prior reports,
vestibular cues can be more precise than visual cues at some frequencies. Our results were also consistent with static Bayesian
optimal integration of visual and vestibular cues.
1
2
Affiliations: Jenks Vestibular Physiology Lab, Mass Eye & Ear Infirmary; Otology & Laryngology, Harvard Med
3
School, Boston MA; Harvard-MIT Program in Speech and Hearing Bioscience and Technology
C2 - Author: W. Michael King
Title: Anticipatory eye movements during active head turns
Abstract: Compensatory counter-rotations of the eyes during head turns are commonly attributed to the vestibulo-ocular reflex
(VOR). A recent study demonstrates that this assumption is not always valid (Shanidze et al 2010). During voluntary head turns,
guinea pigs make ocular counter-rotations with near zero latency that compensate for 80% or more of the head movement. In
contrast, during passive head movements, the mean VOR gain was -0.46 and the latency was 6.9 msec. Animals with bilateral
peripheral vestibular lesions failed to respond to passive head rotations but consistently produced anticipatory eye movements
during voluntary head movements confirming an extra vestibular origin for anticipatory eye movements. We hypothesize that an
efference copy of an intended head movement produces the anticipatory eye movement. This hypothesis is the basis of a new
model of signal processing in vestibular and cerebellar pathways that accurately simulates anticipatory eye movements during
active head turns and VOR responses during passive head movements (King, 2013). Anticipatory responses provide an important
opportunity to study the role of extra vestibular signals in the VOR. The model simulations suggest specific discharge patterns for
vestibular and cerebellar neurons during active and passive head movements that may be tested by neural recordings.
Affiliation: University of Michigan Department of Otolaryngology/Head-Neck Cancer and the Kresge Hearing
Research Institute, Ann Arbor, MI 48109
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C3 - Authors: Alexis Dale, Jerome Carriot, Kathleen E. Cullen
Title: Neural ensemble coding during active versus passive head motion
Abstract: Behavioral studies have revealed that human perceptual detection thresholds rotations are better than those of
individual neurons in early stages of vestibular processing (i.e., afferents and vestibular nuclei, VN). This suggests that pooling the
activity of multiple VN neurons is required to match behavior. In order to accurately model the neuronal output, however, we
must determine whether the responses of individual neurons are independent. Accordingly, we investigated noise correlations
between the activities of pairs of vestibular-only neurons in the VN receiving direct afferent input. In the condition with no
motion present, pairs of nearby (50-150 microns) neurons exhibited minimal synchrony beyond that expected by chance. Thus, in
the absence of stimulation, inputs to VN do not synchronize population activity. This changes, however, during sensory
stimulation. We found that during passive rotations (0.5, 1, 2Hz), noise correlation magnitudes were slightly elevated over
baseline, and that the magnitude increased ~20% with each doubling of rotation frequency. This demonstrates that the high-pass
filtering properties of vestibular-only neurons gate the effect of synchronous afferent inputs depending of frequency. In contrast,
self-generated head rotations resulted in reduced noise correlations relative to any passive condition, suggesting the important
insight that extra-vestibular inputs de-synchronize vestibular-only neurons in the active condition.
Affiliations: Aerospace Medical Research Unit, Dept. of Physiology, McGill University, Montreal, QC
1
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C4 - Authors: Iman Haji Abolhassani , Daniel Guitton and Henrietta L. Galiana
Title: Head-free gaze shifts: platform coordination without trajectory planning
Abstract: Though both eye and head during head-free gaze shifts must collaborate to acquire a target (saccade) and then fixate
on it (slow-phase), their trajectories look very different. This has caused many to question whether a single error signal is
sufficient to drive two platforms along different trajectories. Another observation is that gaze shifts of the same size can produce
variable eye/head trajectories depending on their initial conditions. How does the gaze orientation system accommodate for
different initial conditions? Is trajectory planning or gaze decomposition based on initial conditions necessary to replicate
experimentally observed gaze shifts? Finally, the variability of eye velocity profiles during different-sized gaze shifts is another
characteristic of gaze shifts. Some laboratories have observed double peaks in the eye velocity profiles during large gaze shifts,
while others report instead single-peak eye velocities with a saturation plateau in the position trajectory. It will be shown that all
these features can be replicated in a single non-linear feedback model compatible with physiology. It assumes a shared error map
projecting to platforms with non-linear gain fields, interactions between eye and head brainstem sensorimotor signals, and
dynamic feedback from estimated plant responses to update the ongoing error signal.
1
2
Affiliation: Dept. Biomedical Engineering, McGill University; Dept. Neurology & Neurosurgery, McGill University &
MNI, Montreal
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C5 - Author(s): Mina Ranjbaran & H.L. Galiana
Title: Modelling the VOR with bilateral non-linear cells for context dependence
Abstract: A hybrid nonlinear bilateral model for the horizontal angular vestibulo-ocular reflex (AVOR) is presented. The model
relies on known interconnections between saccadic burst circuits in the brainstem and ocular premotor areas in the vestibular
nuclei during slow and fast phase intervals. In this model it is postulated that nonlinear neural computations appear at the level of
premotor cells in the vestibular nuclei to generate target-distance-dependent VOR gains. A viable switching strategy for the
timing of nystagmus events is proposed. Simulations show that this hybrid model replicates AVOR nystagmus patterns that are
observed in experimentally recorded data.
1
Affiliation: Dept. Biomedical Engineering, McGill University, 3775 University St, Montreal QC H3A 2B4, Canada
2
1
1
C6 - Authors: Prem Jareonsettasin , Dale C. Roberts , David S. Zee
Title: Vestibular secondary nystagmus: a reappraisal of short-term vestibular adaptation
Abstract: Unilateral vestibular lesions produce a tonic imbalance between the right and left vestibular nuclei analogous to a
sustained–low frequency (DC) vestibular stimulus. To prevent persistent unilateral nystagmus, short term adaptation re-adjusts
the steady state of the VOR as modelled by Malcolm and Melvill Jones (1969), Young and Oman (1969) and Furman et al (1989).
Because of the difficulties in changing the parameters of constant (low-frequency) acceleration paradigms, it has been challenging
to elucidate characteristics and dynamics of this adaptive process. We used MRI-induced magnetic vestibular stimulation (Roberts
et al, 2011) and constant acceleration rotatory chair vestibular stimulation paradigms to systematically change adaptation
parameters. We found that the adaptive behaviour required two independent adaptation filters (Tc=100s and Tc=300s) to fit our
data. Adaptation to MVS was significantly more incomplete than to rotatory chair stimulation, which was fitted in our model by
changing the fidelity (leakiness) of the primary adaptation integrator. Our model is able to simulate periodic alternating
nystagmus (PAN) and other forms of vestibular nystagmus such as the reversal phase of the response to a constant-velocity chair
rotation. In addition to providing new insights into vestibular adaptation, these results demonstrate MVS as a novel, non-invasive
method for investigating compensation to tonic vestibular imbalances.
1
2
Affiliations: Department of Neurology The Johns Hopkins Hospital, Baltimore, MD, USA, and Cambridge University,
Cambridge, England
Page 25
D1 - Author: Anna Lysakowski
Title: New Discoveries in the Vestibular Periphery
Abstract: Central vestibular and oculomotor nuclei require input from the vestibular periphery. We have characterized the
vestibular calyx ending surrounding type I hair cells and a cytoskeletal structure found in hair cells. We defined four microdomains
in the calyx ending, corresponding to the diverse functions it subserves: synaptic; apical; initial segment; and heminode
(Lysakowski et al., J. Neurosci., 2011). Each has a set of voltage-gated ion channels, scaffolding and cell adhesion proteins.
Considering the calyx thusly allows us to re-evaluate its purpose. We have also re-examined the striated organelle (SO), located in
the subcuticular region of hair cells (Vranceanu et al., PNAS, 2012), consisting of alternating thick and thin bands (Friedman et al.,
1965; Ross and Bourne, Science, 1983). In type I hair cells, the SO is shaped like an inverted open-ended cone, contacting the
apical cell membrane, separated from the cuticular plate (CP) by large mitochondria. Stereociliar rootlets bend at a 110º angle,
traverse the CP and insert in the plasma membrane opposite the kinocilium. Confocal and EM immunogold experiments,
confirmed by co-IP and mass spectrometry, have demonstrated that antibodies to -actin, actin-binding proteins b-2 spectrin and
a-2 spectrin, and actin-bundling proteins TRIObp and nebulin all label the SO.
Affiliation: Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA. Supported by NIH DC02521, American Foundation for Hearing Research and a Knowles Hearing Center Collaborative Grant.
D2 - Authors: Carriot J & Cullen KE.
Title: Selective encoding of unexpected head tilt by the vestibular nuclei.
Abstract: The ability to distinguish sensory inputs that are a consequence of our own actions from those that result from changes
in the external world is essential for perceptual stability and accurate motor control. We have previously shown that neurons at
the first central stage of the vestibular processing, contributing to vestibulo-spinal reflexes and motion perception, robustly
encode passively applied head rotation/translation in the horizontal plane, while their responses are attenuated during
comparable self-generated head motion. However, natural head movements are not restricted to one plane and create more
complex vestibular stimuli because of the presence of the gravity. Therefore, we hypothesized that the brain uses an internal
model that includes gravity to distinguish between self- versus externally- generated head motion. Here we tested this proposal
by performing single unit recording experiments in alert macaques during passive and active i) head-on-body tilts and ii) head-onbody translations. Interestingly, responses related to actively-generated tilts were significantly attenuated (relative to passively
applied tilts). Moreover, this attenuation was comparable to that observed for active versus passive head translations (67 vs 74%,
p>0.05). Thus, our findings show that the neuronal coding of natural self-motion comprises an elegant computation of an internal
model of active head motion that accounts for gravity.
Affiliation: Dept Physiology & Aerospace Medical Research Unit, McGill University, Montreal, Canada.
Page 26
D3 - Authors: Mohsen Jamali, Jerome Carriot, Kathleen E Cullen
Title: Information transmission in otolith system
Abstract: Understanding how sensory neurons transmit information about relevant stimuli is a fundamental question in
neuroscience. Accordingly, we took advantage of the otolith system which is well-defined anatomically and physiologically and
benefits from easily characterized sensory stimuli (i.e., head acceleration). Moreover, otolith afferents have a broad diversity in
their spontaneous discharge regularity. Here, we employed information theoretic and gain measures to explore the impacts of
background discharge regularity on the encoding of linear acceleration by otolith afferents. Specifically, we investigated how
sensory information is processed in macaques’ primary otolith afferents during translations with sinusoidal as well as broad band
(0-15 Hz) noise linear accelerations. We found an increase in gain for both regular and irregular afferents as a function of the
stimulus frequency; however, the gain enhancement was more prominent for irregular units. In response to noise stimulations,
irregular units conveyed ~2 times more information at higher frequencies (e.g., >6Hz), while in contrast regular afferents only
transmitted slightly greater information at low acceleration frequencies (≤2Hz). These results suggest that while highly sensitive
irregular afferents are more advantageous for transient and dynamic stimuli, the regular units can provide accurate information
when the stimulus is less dynamic (e.g. static tilt).
Affiliation: Department of Physiology, Aerospace medical research unit, McGill University
D4 – Authors: Diana E. Mitchell1, Charles C. Della Santina2, Kathleen E. Cullen1
Title: Shaping central vestibular neuron responses to prosthetic stimulation
Abstract: An implantable prosthesis that stimulates the vestibular nerve branches to restore the sensation of head motion could
greatly benefit vestibular patients. Vestibular prosthetic stimulation can produce reflexive eye and head movements, although
these responses remain subpar. For example, the gain and time constant of the vestibulo-ocular reflex are often lower than
normal when elicited using prosthetic stimulation.
To better understand the effect of prosthetic stimulation on vestibular processing, we recorded from vestibular nuclei
neurons in rhesus monkeys while simultaneously delivering prosthetic stimulation. We quantified the extent to which neurons
were time locked to the stimulus by plotting interspike intervals as normalized polar histograms, such that a net vector strength
of 1 indicates complete time locking. We found that the unit activity of neurons receiving direct input from the stimulated nerve
was highly time locked to electrical pulses quantified by a vector strength of 0.7±0.07. These results suggest that electrical
stimulation synchronously activated the input across the afferent population. In contrast, responses showed markedly less
synchronization when afferents were naturally stimulated. For example, the robust responses produced by applied rotations of
4Hz (±40º/s) were characterized by a vector strength of only 0.2±0.03. We predict that desynchronizing afferent input will
enhance the performance of the vestibular prosthesis.
1
Affiliations: Dept. of Physiology, Aerospace Medical Research Unit, McGill University
2
Dept. of Otolaryngology - Head & Neck Surgery, Johns Hopkins University School of Medicine
Page 27
2
1
1,2
1
D5 - Authors: Adam D. Schneider , Jerome Carriot , Maurice J. Chacron , and Kathleen E. Cullen .
Title: Optimal Sensory Coding of Natural Stimulus Statistics in the Peripheral Vestibular System.
Abstract: Understanding how neurons process sensory information requires not only a characterization of the neuronal
responses, but also the natural stimuli encountered in an organisms sensory environment. This is in part because sensory coding
is adapted to the statistics of natural inputs. The vestibular system has two classes of sensory neurons (regular and irregular), and
we hypothesized that they may be differentially optimized for natural stimuli. We thus measured the head movements of
monkeys during natural behaviors, using a micro-electromechanical systems (MEMS) module sensitive to linear acceleration
along and angular velocity about three axes (fore/aft, lateral, and vertical). Additionally, we fit tuning curves to both classes of
canal afferents, and used information theory to calculate the stimulus distributions for which they are optimized. While one class
has a wider linear range, the other was significantly more optimized to the distribution of natural stimuli. These results challenge
the traditional wisdom that early vestibular pathways are inherently linear, thus motivating a comprehensive rethinking of
sensory coding in the vestibular system.
1
2
Affiliation: Dept. Physiology , Dept. Physics , McGill University, Montreal, Canada
1
2
3
D6 - Authors: Ari Z Zivotofsky ; Avi Caspi ; Carlos R Gordon
Title: Impaired Vestibular Ocular Reflex (VOR) in presymptomatic Spinocerebellar Ataxia Type 3
Abstract: Spinocerebellar Ataxia Type 3 (SCA-3) is an autosomal dominant neurodegenerative disorder for which genetic testing
can reveal those at risk for developing the disease.
Objective: to check if eye movements can be used as biomarkers to quantify the appearance and progress of the disease even
presymptomatically. Methods: Using the magnetic search coil technique we recorded saccades, smooth pursuit, and VOR of 10
symptomatic SCA-3 patients and 4 subjects at risk for developing SCA-3. Three of at risk subjects were genetically tested and
found to have expanded “CAG” repeats in the ATXN3 gene. The fourth is a sibling of a symptomatic MJD patient who has declined
genetic testing. Results: We found that the four at risk subjects have a reduction in the gain of the VOR as measured using the
head impulse test (HIT). Nonetheless, we did not find any deficit in either their saccades or smooth pursuit. In contrast, all of the
symptomatic patients had saccadic and smooth pursuit deficits, in addition to impaired VOR. Conclusions: Individuals at risk for
developing SCA-3 can be asymptomatic for years before receiving formal diagnosis. Our preliminary results suggest that the HIT
may provide biomarkers useful in tracking phenotypic change in such individuals.
1
2
Affiliations: Brain Science, Bar Ilan University, Ramat Gan; Department of Electrical and Electronic Engineering, Sami
3
Shamon College of Engineering, Ashdod; Dept Neurology, Meir Medical Center, Kfar Saba and Sackler Faculty of Medicine, Tel
Aviv University, Tel Aviv, Israel.
Page 28
LIST of Symposium Attendees
Country/Name
email
Affiliation or location
Heather Armstrong
heather.armstrong@mail.mcgill.ca
Dept. Biomedical Eng., McGill U., Montreal,
Quebec
Martin Ballantyne
mjballantyne46@hotmail.com
Oshawa, Ontario
CANADA
Hamilton, Ontario
Mark Ballantyne
Edward Block
block@ucalgary.ca
Dept of Clinical Neurosciences & Hotchkiss Brain
Institute, University of Calgary, Alberta
Jerome Carriot
jcarriot@gmail.com
Dept. Physiology, McGill Univ., Montreal, Quebec
Kathy Cullen
kathleen.cullen@mcgill.ca
Alexis Dale
alexis.dale@mail.mcgill.ca
Bill Fletcher
Robert French
Henrietta Galiana
Aron Gonshor
Diego Guarin Lopez
Daniel Guitton
Iman Haji
Kian Jalaleddini
Bill.Fletcher@albertahealthservices.ca
french@ucalgary.ca
Henrietta.galiana@mcgill.ca
arongonshor@gmail.com
diego.guarinlopez@mail.mcgill.ca
Daniel.guitton@mcgill.ca
iman.hajiabolhassani@mail.mcgill.ca
seyed.jalaleddini@mail.mcgill.ca
Dept. Physiol. & Pharmacology, Univ. Calgary,
Alberta
Quebec
Montreal, Quebec
Quebec
Dept. Neurol & Neurosurgery, MNI & McGill Univ.,
Montreal, Quebec
Quebec
Quebec
Mohsen Jamali
mohsen.jamali@mail.mcgill.ca
Francis Jones
fjones@eos.ubc.ca
University British Columbia, Vancouver BC
Kitty Jones
kittyjones@shaw.ca
Calgary, Alberta
Geoffrey Melvill Jones
gmelvill@ucalgary.ca
Robert Kearney
robert.kearney@mcgill.ca
Quebec
Prasun Lala
prasun@pklala.net
Montreal, Quebec
Beth Lange
beth.lange@albertahealthservices.ca
Alberta health Services, Calgary, Alberta
George.Mandl@mcgill.ca
George Mandl
mergler.donna@uqam.ca
Groupe de Recherche sur le Système Nerveux
Central (FRSQ), & Dept of Physiology, Univ. de
Montréal, Quebec
Université du Québec à Montréal,
(UQAM), Quebec
Diana Mitchell
diana.mitchell@mail.mcgill.ca
Caroline Paquette
caroline.paquette@mcgill.ca
Kinesiology & Physical Education, & Neurology &
Neurosurgery, McGill University, Montreal QC
Marina Martinez
Donna Mergler
m.martinez.pro@gmail.com
Page 29
Quebec
Groupe de Recherche sur le Système Nerveux
Central (FRSQ), & Dept of Physiology, Univ. de
Montréal, Quebec
Mina Ranjbaran
mina.ranjbaranhesarmaskan@mail.mcgill.ca
Serge Rossignol
serge.rossignol@umontreal.ca
Adam Schneider
adam.schneider@mail.mcgill.ca
ehsan.sobhani@mail.mcgill.ca
Quebec
doug.watt@mcgill.ca
Wong elizabeth.looi@mcgill.ca
Dept. of Ophthalmology, McGill University,
Montreal, QC
cgordon@post.tau.ac.il
Dept Neurology, Meir Medical Center, Kfar Saba
and Sackler Faculty of Medicine, Tel Aviv Univ, Tel
Aviv, Israel
Prem Jareonsettasin
pj280@cam.ac.uk
Cambridge University, Cambridge, England
Johannes van der Steen
steen4@xs4all.nl
Pierre-Paul Vidal
ppvidal@me.com
Ehsan Sobhani Tehrani
Douglas Watt
Mrs Elizabeth Wong
EUROPE
Carlos Gordon
Erasmus University Medical Center, Dept.
Neuroscience, Rotterdam, The Netherlands
CeSeM, CNRS UMR 8194, Université Paris
Descartes, Paris, France
JAPAN
Yoshiro Wada
wada@naramed-u.ac.jp
Department of Physiology, Nara Medical
University, Kashihara 634-8521, Japan
USA
Gammon Earhart
earhartg@wustl.edu
Ruth-Anne Eatock
RuthAnne_Eatock@meei.harvard.edu
Jay Goldberg
Stephanie Haggerty
jgoldber@bsd.uchicago.edu
hastepha@umich.edu
Fay Horak
horakf@ohsu.edu
Christina Hui-Chan
chuichan@uic.edu
Faisal Karmali
Ed Keller
W. Michael King
faisal_karmali@yahoo.com
elk@ski.org
wmking@umich.edu
John Leigh
rjl4@case.edu
Rick Lewis
Richard_Lewis@meei.harvard.edu
Anna Lysakowski
alysakow@uic.edu
Prog in Physical Therapy, Dept Neurology, Dept of
Anatomy and Neurobiology, Washington Univ in
St. Louis, Sch of Medicine, St. Louis, MO
Dept. Otology & Laryngology and Neurobiology,
Harvard Medical School
Department of Pharmacological & Physiological
Sciences, University of Chicago, Chicago, IL
Dept of Biomedical Engineering, University of
Michigan, Ann Arbor, MI
Oregon Health and Science University, Dept. of
Neurology, Portland OR
Department of Physical Therapy, University of
Illinois at Chicago
Jenks Vestibular Physiology Lab, Mass Eye & Ear
Infirmary; Otol & Laryngol, Harvard Med School,
Boston MA
Professor Emeritus, SKI,
University of California, Berkeley CA
Department of Otolaryngology/Head-Neck Cancer,
Univ. of Michigan & Kresge Hearing Res Inst, Ann
Arbor, MI
Department of Veterans Affairs Medical Center
and Case Western Reserve University, Cleveland
Ohio
Jenks Vestibular Physiol Lab, Mass Eye and Ear
Infirmary & Dept Otology & Laryngol, Harvard
Medical School , Boston, MA
Dept. of Anatomy and Cell Biology, Univ. of Illinois
at Chicago, IL
Page 30
Dan Merfeld
dan_merfeld@meei.harvard.edu
Harvard Medical School & Jenks
Vestibular Physiol Lab, Cambridge, MA
Lloyd Minor
lminor@stanford.edu
Stanford Medicine, Stanford, CA
dzee@jhu.edu
Contact via David Zee
David Robinson
Angus Rupert
angus.rupert@us.army.mil
Mark Shelhamer
mjs@dizzy.med.jhu.edu
John I Simpson
John.Simpson@nyumc.org
Larry Young
lry@MIT.EDU
David Zee
dzee@jhu.edu
U.S. Army Aeromedical Research Lab, Ft. Rucker
AL
Dept Otolaryngology & Dept of Biomed. Eng.,
Johns Hopkins School of Medicine, Baltimore MD
Physiology & Neuroscience, NYU Medical Center,
New York, NY
Dept. Aeronautics. & Astronautics,
MIT, Cambridge MA
Dept Neurology, Johns Hopkins Hospital,
Baltimore MD
Page 31

Final Program Sensing Motion for Action

Transcription

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