Frequently asked questions Psychology 1010.06M A Biologically-Oriented

Psychology
1010.06M
A Biologically-Oriented
Introduction to
Psychology
Instructor: Professor Jennifer Steeves
Frequently asked questions
• Class is full, still try to enroll
• Can you post the slides because I can’t take
notes and listen… or I missed the last class…
• Am I responsible for the text, the lectures,
and the videos that you show in class?
• Don’t understand the assignment
• Where is the assignment posted?
e-mail: steeves@yorku.ca
telephone: 416-736-2100 X20452
Web: www.yorku.ca/steeves/1010M_2009
Review from Last Class
Genetic Explanations of Behavior
– Alcoholism
• twin studies
• adoption studies
• artificial selection studies
Evolutionary Explanations of Behavior
– ultimate vs. proximate causes
– altruism
•
•
•
•
cooperation vs. altruism
kin selection theory
selfish genes?
reciprocal altruism
Sample Question
factual:
A negative correlation means that:
a) high values of one variable are associated
with low values of the other.
b) high values of one variable are associated
with high values of the other.
c) low values of one variable are associated
with low values of the other.
d) there is no relationship between the two
variables.
e) none of the above
Sample Question
According to kin selection theory, animals that
engage in altruistic acts, such as warning
others of an approaching predator, are:
a) actually benefiting themselves as individuals
b) not actually reducing their own chances of
survival and reproduction
c) helping to ensure the survival of the genes
they have in common with close relatives
d) expecting other animals to return the favour
at some future time
Sample Question
conceptual:
It is quite likely that the more classes students
miss, the lower their test grades tend to be.
This relationship illustrates a(n):
a) negative correlation
b) positive correlation
c) coefficient of correlation.
d) zero correlation.
e) a perfect positive correlation.
1
Sample question
applied:
Julie has found that the number of hours she sleeps each night
is related to the scores she receives on quizzes the next
day. As her sleep approaches eight hours, her quiz scores
improve; as her sleep drops to five hours, her quiz scores
show a similar decline. Julie realizes that:
a) there is a negative correlation between the number of hours
she sleeps and her quiz grades.
b) there is a positive correlation between the number of hours
she sleeps and her quiz grades.
c) her low quiz scores are caused by sleep deprivation the
night before a quiz.
d) she should sleep about ten hours a night to ensure 100
percent quiz grades.
e) high quiz scores are due to adequate sleep the previous
night.
The Brain: Source of Mind and Self
1.
The Nervous System
a.
b.
c.
2.
~3 lbs
~2% of body weight
20% of body’s oxygen
consumption
Peripheral nervous system
Central nervous system
Hierarchical Brain: structures and functions
Neural Bases of Behaviour
a.
b.
c.
3.
Human Brain
Neurons
Electrochemical process
Synaptic transmission
How we can study the brain
Show video P&B
CNS vs. PNS
Spinal
Cord
Brain
Nerves
Central Nervous System
• brain + spinal cord
Peripheral Nervous System
• nerves connecting CNS to
muscles and organs
Peripheral Nervous System
Peripheral Nervous System
Skeletal
(Somatic)
Autonomic
Sympathetic
Parasympathetic
2
Somatic System
Reflexes
• Sensory Neurons
– input from body to CNS
• Motor neurons
– output from CNS to
control muscle
movements
• Interneurons
– sensory-motor relay
within CNS
• Both voluntary and
reflex movements
• Spinal reflex arc
Peripheral Nervous System
Autonomic Nervous System
Peripheral Nervous System
Skeletal
(Somatic)
Autonomic
Sympathetic
Parasympathetic
The Sympathetic Nervous System
in Action
Sympathetic
• “fight or flight”
Parasympathetic
• “rest and digest”
Central Nervous System
Spinal
Cord
Brain
• brain
• spinal cord
Nerves
3
Spinal Cord
Brain
Spinal injuries
• input can’t get in
• output can’t get out
• different levels wired to
different body parts
– quadraplegic vs. paraplegic
Brain Stem and Thalamus
Brainstem and Midbrain
• postural reflexes
• vital reflexes (breathing
rate, heart rate)
• movements
• sleep & arousal
Thalamus
Cerebellum
• relay or gateway or
“traffic officer”
• sensory messages
directed to higher
centres (except
olfaction)
• “little brain”
• traditionally thought to help you “walk and chew gum at
the same time (balance and muscle coordination)
• scientists now realize it’s much more diverse and
sophisticated-- involved in higher cognitive tasks
4
Basal ganglia
Limbic system
• amygdala
– emotion
• hippocampus
– memory formation
• hypothalamus
–
–
–
–
–
–
• movement
• Parkinson’s disease affects BG circuits
– tremor
– rigidity
– problems initiating movements
regulate body functions
autonomic NS
hormones
drives
emotion
“4 Fs”
• pituitary gland
– receives messages from
hypothalamus
– Then sends hormones to
endocrine glands
Fig 5.7
Cerebral Cortex
Localization of Function
Phrenology
-bumps on the head
said to be related to
personality traits
• cortex = bark = outer surface of brain
Localization of Function
The Case of Phineas Gage
“Dr. Penfield, I smell toast!”
•
•
•
•
Wilder Penfield, Montreal Neurological Institute
Epilepsy surgery
Stimulate brain
can invoke movements, sensations, emotions, memories,
experiences
5
Each hemisphere is
divided into 4 lobes
Occipital Lobe
Frontal
Parietal
Occipital
• Input from eyes via
optic nerve
• Contains primary visual
cortex
• Outputs to parietal and
temporal lobes
Occipital
Lobe
Primary
Visual
Cortex
Temporal
Parietal Lobe
Temporal Lobe
• Inputs from multiple
senses
• Auditory cortex gets input
from the ears
• Visual Input from occipital
lobe
• Recognition and Memory
–
–
–
–
Auditory
Cortex
speech recognition
face recognition
word recognition
memory formation
Temporal
Lobe
Somatosensory
Cortex
Parietal
Lobe
• Output to frontal lobe
• Sensorimotor control
– hand-eye coordination
– eye movements
– attention
• Outputs to limbic system,
basal ganglia, and
brainstem
Frontal Lobe
• No direct sensory input
• Includes motor cortex
• Includes motor speech
area (Broca’s area)
• Important for planning
and sequencing ideas
– Input from touch to
somatosensory cortex
– Input from vision via
occipital lobe and
audition via temporal
lobe
Brain has 2 Hemispheres
Frontal Lobe
Broca’s
Area
Motor
Cortex
6
Sensory Information
sent to opposite
hemisphere
Contralateral Motor Control
• Movements controlled
Motor Cortex
by motor area
• Right hemisphere
controls left side of
body
• Left hemisphere
controls right side
• Motor nerves cross
sides in spinal cord
• Sensory data crosses over
in pathways leading to the
cortex
• Visual crossover
– left visual field to right hemisphere
– right field to left
• Other senses similar
The visual fields NOT the eyes cross over!!!
Corpus Callosum
Somatosensory Cortex
Corpus Callosum
• Major ( but not only)
Medial surface of right hemisphere
pathway between sides
• Connects comparable
structures on each side
• Permits data received on
one side to be processed
in both hemispheres
• Aids motor coordination Corpus Callosum
of left and right side
• What happens when the corpus
callosum is cut?
• Sensory inputs are still crossed
• Motor outputs are still crossed
• Hemispheres can’t exchange data
• Scientific American video
The ‘Split Brain’ studies
• Special apparatus
– picture input to just one side
of brain
– screen blocks objects on
table from view
Verbal
left
hemisphere
Nonverbal
right
hemisphere
7
Cell types in the brain
1) Glia
–
–
–
–
“glue”
support cells
constantly replacing themselves
~1 trillion glial (1,000,000,000,000) cells
2) Neurons
– information processing cells
– less able than other cells to replace themselves
– ~100 billion (100,000,000,000) neurons
Glia
support cells
– provide insulation
• increase speed of neurons
– provide nutrients
– keep toxic substances out
(blood-brain barrier)
– support neurons
– clean-up and repair
Information Flow
dendrites
– many dendrites per neuron
(“dendritic tree”)
– collect information from other
neurons
cell body
– one cell body per neuron
– normal cell regulation functions
– axon hillock sums inputs
axon
– one axon per neuron
– transmit signal
• can be over long distances (e.g.,
sensory neurons in toe)
– end feet (axon terminals)
communicate information to the
dendrites of other neurons
(synapses -- stay tuned)
8
Axons
Structure
indicates function
Let’s take a closer look at what goes on in the
axons…
sensory neurons
cortex
cerebellum
– relay information
– not many dendrites
interneurons
– collect and integrate
information
motor neurons
– collect information
– long axons
Ion Distribution-- resting potential
Let’s Zoom in on an Axon
Outside
Membrane
Inside
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
• Because of the A- inside and Na+ outside, there is a
voltage across the membrane
• Inside is 70 mV more negative than outside
• Resting voltage = -70 mV
So What?
• When nerve cell is stimulated → sudden
inflow of + charged Na+ across membrane
followed by outflow of K+
• → brief change in electrical voltage
• → The action potential
Membrane Potential (mV)
• By storing up energy, you can use it later
• Analogy: water dam
+50
Resting Potential
0
Resting membrane
potential
-70
Time 
9
Hyperpolarization
+50
Membrane Potential (mV)
Membrane Potential (mV)
+50
0
-70
Depolarization
0
-70
Time 
Time 
The Action Potential
Membrane Potential (mV)
+50
Threshold of
excitation
Na+ channels close
K+ channels open
Na+ enters
cell
K+ leaves cell
0
Larger
depolarization
Hyperpolarization
-60
-70
Nothing
happens At threshold,
Small
Voltage-gated
depolarization
Na+ channels open
below threshold
The cell won’t produce another action
potential until the resting potential has
been restored.
This is called the cell’s refractory period.
Resting membrane
potential restored
How is a Neuron Like a Toilet?
• threshold
• all-or-none
• refractory period
An action potential either occurs or it
doesn’t ... and if it occurs, it occurs
at full amplitude.
This is called the All-or-none Law
10
Rapid Action Potentials
• An action potential takes less than 1/1000 second
Action Potential Propagates
= depolarization (+)
• You can have many action potentials in a row
– sometimes we’ll call action potentials “spikes”
– sometimes we describe an AP as the neuron “firing”
Action potentials on their own are quite
slow and metabolically expensive
Go Faster!
1. Wider diameter axons
– the squid’s solution -- giant axons (1 mm diameter)
What can make them go faster?
Yeah, that’s fine if you’re a squid and don’t have a lot of neurons!
2. Saltatory conduction
Saltatory Conduction
Action Potential Propagates
= depolarization (+)
~30 metres/sec
~120 metres/sec
11
How Does Saltatory Conduction Work?
• Glia wrap around axon
• This insulation is called
myelin
• Nodes of Ranvier
– Gaps between glia
• Saltatory conduction
– Action potential jumps
between nodes
Myelin
• Myelin is mostly fat
• Fat is white
• White matter contains myelinated axons
gray matter
• dendrites, cell bodies, end feet
white matter
• axons
Myelinization
• not all neurons are covered in myelin at birth
• myelin develops in different regions at
different times
• simpler areas (sensory and motor) become
myelinated first
• myelination can continue until ~age 20 in
areas involved in abstract thinking
Multiple Sclerosis
• decay of myelin sheaths
• impaired sensation and
movement
• axons are exposed and
break down
• sclerosis = hardening
• may be an autoimmune
disorder
Yes, you CAN learn to think better, stronger and FASTER!
What makes an action potential begin?
Axon hillock
• “little hill” at the junction of
the cell body and the
beginning of the axon
• gathers information from
dendrites
• sort of like a “vote counter”
12
Synapses
Postsynaptic Potentials
= the connection between the axon of one
neuron and (usually) the dendrite of another
• Postsynaptic
– on the dendrites (or sometimes the cell body) of the
receiving neuron
• Potential
– voltage difference
• Excitatory post-synaptic potentials (EPSPs)
– “yes” votes
presynaptic
membrane
• Inhibitory post-synaptic potentials (IPSPs)
– “no” votes
synaptic cleft
postsynaptic
membrane
What happens when the action
potential reaches the end?
Synapses
presynaptic
membrane
synaptic cleft
postsynaptic
membrane
Receptors: “Lock and Key”
neurotransmitter
molecules
Synaptic
Transmission
precursor 1
SYNTHESIS
breakdown
product
transmitter
DEGRADATION
STORAGE
synaptic
vesicles
INACTIVATION
breakdown
product
2
7
5
REUPTAKE
6
RELEASE
3
4
RECEPTOR
BINDING
PSPs
13
Receptor binding
Drug Actions
• opens ion
channels
• Drugs can act at any stage of synaptic
transmission
• Agonists
– drugs that increase the effectiveness of synaptic
transmission
• Antagonists
– drugs that decrease the effectiveness of
Normal
Acetylcholine
(ACh) Drugs
• neurotransmitter in the
PNS (neuromuscular
junction) and CNS that
involved in motor
control, learning and
memory, and sleep and
dreaming
Antagonist
Agonist
Serotonin
• serotonin
– neurotransmitter involved
in emotions and dreaming
• depression
– common disorder
• 5% of population
depressed at any one
time
• 30% depressed at some
point during lifetime
• higher incidence among
women than men
– seems to be due to
reduced serotonin
• selective serotonin
reuptake inhibitors (SSRIs)
– e.g., Prozac, Paxil, Zoloft,
– selective for serotonin
– reuptake inhibitors prevent
serotonin from being taken
back up so it remains in
the synaptic cleft longer
Brief Overview of Neurotransmitters
NEUROTRANSMITTER
FUNCTIONS
DISEASES
DRUGS
Acetylcholine
Motor control over muscles
Learning, memory, sleeping & dreaming
Alzheimer’s ()
Nicotine ()
many toxins (e.g., spider
venom )
Norepinephrine
Arousal and vigilance, eating behavior
Dopamine
Reward and motivation, Motor control over voluntary movement
Schizophrenia ()
Parkinson’s ()
L-dopa for Parkinson’s ()
Amphetamine ()
Cocaine ()
Antipsychotics ()
Serotonin
Emotional states and impulsiveness, dreaming
Depression (), mania (
)
Prozac and other SSRIs ()
Ecstasy ()
LSD ()
Psilocybin (mushroom) ()
GABA
Inhibition of action potentials; anxiety and intoxication
Glutamate
Enhances action potentials, learning and memory
Adenosine
relaxation (sympathetic parasympathetic return)
Endorphins
Pain reduction, reward
Amphetamine ()
Valium ()
Barbiturates (“downers”) ()
Alcohol ()
Caffeine ()
Heroin
Morphine
Jogging
Chocolate
Substance P
Pain perception
Chili peppers
Anandamide
Enhancing forgetting?
THC (marijuana)
Chocolate (a lot!)
14
What can you do with a neuron?
Neural Computing
1,000 to 10,000 synapses per neuron
~3 neurotransmitters/neuron (range ~2-5)
4 neurotransmitters x 3 states = 81 states
~100 billion (100,000,000,000) neurons
• Perform computations
• Make muscles twitch
• Make glands squirt
Single-Neuron Recording
• Stick a thin electrode into an animal’s brain (rat, cat,
monkey)
• record action potentials from a single neuron
• measure neuronal firing under a range of conditions
EEG (electroencephalography)
• Measure voltage differences with electrodes
placed on the scalp
• “Like holding a microphone over a stadium”
Example: Head direction neuron in limbic system
EEG (electroencephalography)
Waveforms vary with brain states
Event-related Potentials (ERPs)
Epileptic seizure
15
Neuropsychological Patients
MRI vs. fMRI
• Determine the performance deficits of patients who
have lesions (brain damage) to a specific part of the
brain
• Examples
MRI studies brain anatomy.
Functional MRI (fMRI)
studies brain
function.
– Phineas Gage
– Broca’s aphasia
– split brain patients
Functional MRI
Brain Imaging: Anatomy
CAT
Photography
PET
MRI
Big magnet
(typical magnet is 60,000X earth’s magnetic field)
+ radio waves
MRI vs. fMRI
good resolution
(1 mm)
MRI
PET and fMRI Activation
fMRI
poorer resolution
(~3 mm but can be better)
one image
…
many images
(e.g., every 2 sec for 5 mins)
↑ neural activity
 ↑ blood oxygen  ↑ fMRI signal
16
Transcranial Magnetic
Stimulation (TMS)
• Virtual, temporary lesions
• Wire coil on head-- magnetic pulse-- causes
neurons to fire
• Video clip
17