Transcript Document 7154706

Neuroscience, Genetics and Behavior
True or False?

“Basic biological processes underlie all
human behavior.”

Various branches of psychology rest on
this foundation.
Biological Psychology
(or Psychobiology)
The most significant transformation in
modern psychology
 AKA Biopsychologists, behavioral
neuroscientists, behavior geneticists,
physiological psychologists,
neuropsychologists…

An intro to neuroscience…
Explain the following…
1.
2.
3.
4.
“Modern psychology views each
individual as a biopsychosocial system.”
“Everything psychological is
simultaneously biological.”
“The mind is what the brain does..”
“A brain simple enough to be understood
is too simple to produce a mind able to
understand it.”
Introducing the

Simple definition:


neuron…
a nerve cell
The incredible neuron….
basic unit of information processing and the
building block of the brain. (and nervous
system)
 Working together with other neurons and cells
throughout the body, it allows us to think,

feel, move and breathe.
A vastly complex system…
Facts about neurons:

100 billion neurons in the human brain and
CNS! (and 400 trillion synapses!)
A
grain of sand-size part of the human brain
holds 100,000 neurons!
Neural Structure

Dendrite (receives impulse)


Branching extensions of a neuron / receive messages
/ conduct impulses toward the cell body
Axon (transmits impulse)

extension of a neuron, ending in branching terminal
fibers, through which messages are sent to other
neurons or to muscles or glands
Remember: “Axons speak, dendrites listen…”

Myelin Sheath (speeds impulse)


a layer of fatty cells segmentally encasing the fibers of
many neurons
Speeds transmission of neutral impulses
Neural Structure

So what happens when the myelin sheath
begins to wear out?
 Alzheimer's
(impedes transmissions affecting
thought process)
 Multiple sclerosis: interferes with muscle
control (as message to muscles is impeded..)
Neural Structure
Neural Communication
“an electrochemical process…”

“Neural communication is a conversation
between cells that generates our
thoughts, actions, moods and memory.”
Neural Communication

Action Potential
a neural impulse; a brief electrical charge that
travels down an axon
 Stimulated when neuron receives signals from
sense receptors stimulated by heat, pressure
or light
 generated by the movement of positively
charged atoms in and out of
channels in the axon’s membrane

Neural Communication
“What one neuron tells another neuron is simply how
much it is excited.”

Each neuron has a threshold…


the level of stimulation required to
trigger an action potential (or neural impulse)
Threshold is determined by excitatory
(accelerator) and inhibitory (brakes)
triggers that determine the action
potential (neural impulse)
Neural Communication…
Neurons generate electricity from chemical
events (like batteries)
 The chemistry to electricity process
involves the exchange of ions


Ions: electrically charged atoms
Ions…

Resting Potential




Fluid inside a resting axon has negatively charged
atoms
Fluid outside the axon membrane has positively
charge atoms
Natural state of inside / outside ions = resting
potential
Axon’s surface is selectively permeable (it
decides what it allows in..)
Reaching a Neuron’s Threshold…
When the neuron fires…
 Axon opens gates (selectively permeable)
and +charged sodium ions flood the
membrane
 +sodium ions cause depolarization
 Depolarization causes reaction as axons pass
the impulse down the chain (like dominoes)
 Opens and closes 100-1000 times /second!

Reaching a Neuron’s Threshold…

Refractory Period
 Once
impulse has been passed, the axon
pumps +ions back out of membrane, and
thus recharges

All or none response
 Increased
stimulus does not increase the
action potential’s intensity (a gun either fires
or doesn’t)
Neural Communication
Cell body end
of axon
Direction of neural impulse: toward axon terminals
Neural Communication

Synapse (Where the action is…)



gap between the axon tip of the sending neuron and
the dendrite or cell body of the receiving neuron
tiny gap at this junction is called the synaptic gap or
cleft (less than a millionth of an inch!)
Neurotransmitters



chemical messengers that cross the synaptic gaps
between neurons
neurotransmitters bind to receptor sites (“lock and
key”) on the receiving neuron, thereby influencing
whether it will generate a neural impulse
Thus ions passed on to new neuron: exciting
or inhibiting its readiness to fire..
Neural Communication

Reuptake
 Excess
neurotransmitters are reabsorbed by
the sending neuron
Neural Communication
Neurotransmitters
About 75 have been discovered
 We will study 7-8

Neurotransmitters
(Take notes on last 2 listed)
Neurotransmitters
GABA


Inhibitory
neurotransmitter
Undersupply = seizures,
tremors, insomnia
Glutamate





Excitatory
neurotrasmitter
Invovled in memory
Too much = migraines,
seizures
Excitotoxicity: “excite a
neuron to death” (glial
cells help prevent…)
Chinese food- MSG
(glutamate) = headaches
Neurotransmitters

Acetylcholine [ah-seat-el-KO-leen]



ACh
triggers muscle contraction (movement,
learning, memory)
Undersupply = Alzheirmer’s
Neurotransmitters

Endorphins [en-DOR-fins]





“morphine within”
natural, opiate-like neurotransmitters
linked to pain control and to pleasure
“Runners high”
Opium, heroine addicts: brain stops
producing natural opiates, thus
“withdraws”
Neurotransmitters…

Norepinephrine
 Mood
 Too
much = mania / too little = depression
 Imbalance = bipolar disorder
Neurotransmitters

Serotonin
 Sleep,
eating, mood
 Related to depression
 Prozac (anti-depressant drug) raises serotonin
levels
Neurotransmitters

Dopamine
 Perceptual
awareness, muscle control
 Too much = Schizophrania (up to 6x more
dopemine)
A
Beautiful Mind / The Soloist
 Too little = Parkinson’s Disease (tremors:
Muhammad Ali)
Drugs Affect Neurotransmission

Drugs can be used to affect
communication at the synapse
 Agonists
excite, or mimic the
neurotransmittors / or block reuptake
(drug
addicts and withdraw)
 Antagonists block, or inhibit
neurotransmitters signal (examples=Botox/
botulism blocks Ach)
A complicated process: Brain has blood-brain
barrier that blocks out unwanted chemicals
Neural Communication
Serotonin Pathways
Dopamine Pathways
Remember…

Communication within the neuron is…….
 Electrical

Communication between neurons is….
 chemical
Glial cells (Glia)
Make up 90% of
brain’s cells
 Protect, nourish
neurons
 Current research
suggests possible
action potentials,
debate as to role…
 See p. 45: Alchemy of

Mind
An Alchemy of Mind
Explain fully each of the following quotes from your
reading.
 “Neurons speak an elite pidgin neither chemical nor
electrical but a lively buzz that joins the two, an
electrochemical lingo all their own.”
 “It is important to realize that what one neuron tells
another neuron is simply how much it is excited.”
 It is a small liquid space, as is the air between two
whispering lovers, yet so much life happens there.
Each junction is a bazaar full of commerce, intrigue
and possibility. In the brain, everything depends on
almost nothing, a lively space….”
 “Coexisting as they must, both neurons and glia are
dependable, dependent… central to the brain’s social
fabric and perpetual hum.”
The Nervous System

Nervous System
the body’s speedy, electrochemical
communication system
 consists of all the nerve cells of the PNS and
CNS


Central Nervous System (CNS)


the brain and spinal cord (encased in bone)
Peripheral Nervous System (PNS)

connect the central CNS to the rest of the
body’s sense receptors
The Nervous System
Nervous
system
Central
(brain and
spinal cord)
Peripheral
Autonomic (controls
automatic action of
internal organs and glands)
Somatic (Skeletal) (controls
voluntary movements of
skeletal muscles)
Sympathetic
(arousing: flight or fight)
Parasympathetic
(calming)
The Autonomic Nervous System

Autonomic Nervous System


part of the PNS: controls the glands and the
muscles of the internal organs (involuntary)
A Dual System

Sympathetic Nervous System


arouses the body, mobilizing its energy in stressful
situations (“Fight or flight”, or “sympathy in crisis”)
Parasympathetic Nervous System


calms the body, conserving its energy
“paramedics to calm down”- lowers heartbeat etc.
The Nervous System
The Nervous System
The Peripheral Nervous System

Links CNS to body’s sense receptors
 For
each of the following, identify it as a
function of the Somatic or Autonomic Nervous
System.
 Sneezing
 Turning the page
 Scratching your head
 Breathing
 Kissing your date
 Digesting your food
Communication in the Nervous System

Nerves
neural “cables” containing millions of axons
 part of the PNS (carry PNS info)
 connect the CNS with muscles, glands, and
sense organs
 Extend through the body

Communication in the Nervous System

3 neurons that carry info in the
nervous system

Sensory Neurons (afferent: millions!)


Motor Neurons (efferent: millions)


neurons that carry incoming information from the
sense receptors to the central nervous system
carry outgoing information from the CNS to
muscles and glands
Interneurons (billions!)

CNS neurons that internally communicate / process
sensory and motor neurons (most complex)
The Central Nervous System
“The motherboard of our humanity…”
 10’s of billions of neurons
 Brain and spinal cord
 Spinal cord: Information highway
connecting PNS to the brain

Reflexes

Spinal Reflex: Autonomic response to stimuli
(Single sensory neuron, single motor neuron,
interneuron:…..Brain’s not involved!)
Pain Reflex

Sensory neuron, interneuron, motor neuron
 a simple, automatic, inborn response to a sensory stimulus
The Brain
Center for all sensory information and voluntary
movement (receives, interprets, decides…)
 Without the brain…no pain or pleasure, no
voluntary movement

Neural Networks
A Complex Mystery…
Neurons in the brain
connect with one
another to form networks
Inputs
The brain learns by modifying
certain connections in
response to feedback

Neural Networks
interconnected neural
cells
 with experience,
networks can learn, as
feedback strengthens
or inhibits connections
Outputs
that produce certain
results
 computer simulations
of neural networks
show analogous
learning

In other words…

“Neurons that fire together... wire
together.”
The Endocrine System
The body’s 2nd communication system
 Interconnected with nervous system

Endocrine System
ES glands produce hormones
 Hormones travel through bloodstream to
affect body
 Influences growth, mood, metabolism,
reproduction etc.
 Thus ES works to keep body in balance in
response to stress, exertion, thoughts etc.
 “Snail mail”- Much slower to process,
several seconds, but lasts longer…

Important Glands…

Pituitary Gland (the master gland..)
 Pea
sized, in middle of brain
 Influences growth
 Influences other Endocrine glands’ release of
hormones
 Controlled by hypothalamus (brain)
 Brain – pituitary – other glands – hormones –
brain (complex system: blend of Endocrine
system and nervous systems)
Pituitary Gland
Adrenal Glands
Located on top of kidneys
 Release epinephrine and norepinephrine
(adrenaline and noradrenaline)
 Heart rate, blood sugar, blood pressure
etc.

Adrenal Glands
What do you know about the human
brain?

1.
2.
3.
4.
5.
Answer the following as true or false.
The larger the brain, the smarter the animal.
The brain’s structure is a better indicator of
intelligence than it’s size.
The right side of the brain controls the right
side of the body, and so on with the left.
You fall in love with your heart, not your brain.
Your brain uses 20% of your body’s energy,
but makes up only 2% of your body’s weight.
What do you know about the human
brain?

6.
7.
8.
9.
10.
True-False continued…
Your brain is about the size of a cantaloupe and is
wrinkled like a walnut.
Your brain feels like a ripe avocado and looks pink
because of the blood running through it.
The baby’s brain grows 3x in size during its first year.
At birth, the human brain weighs 4/5 of a pound, while
an adult’s weighs about 3 pounds.
Your brain generates about 25 watts of power while
awake- or enough to illuminate a light bulb.
The typical human brain…
o
o
o
o
o
contains about 100
billion neurons
consumes about ¼ of
the body’s oxygen
spends most of the
bodies calories
Is 70% water!!!
weighs about 3 pounds
The Brain

Lesion
tissue
destruction
 a naturally or
experimentally
caused
destruction of
brain tissue

Neuroimaging Techniques
“Mapping the brain”
Electroencephalogram (EEG)
Detects Brain Waves
Scans / measures
electrical activity
across brain
 can specify waves
to specific stimulus
 Sleep research


CAT (computed tomography) Scan



Multiple x-ray pictures = 3D image of brain structure
Structure only- not function
Tumors, physical abnormalities

PET (positron emission tomography) Scan
Can measure amount and movement of
chemicals in the brain (glucose)
 Check brain’s activity to specific tasks (the
more used, the more activity…)
 Neurotransmitters and drugs


MRI (magnetic resonance imaging)
Like CAT, but used magnetic fields to measure
density and location of brain material
 soft tissue; allows us to see structures within
the brain

MRI Scan
FMRI (Functional MRI) Reveals brains’
functioning as well as its structure (IOW:
MRI + PET)
 Watches brain “light up” by concentrations
of blood flow to specific areas

The Old Brain (hind brain)
“Parts shared with Distant Ancestors”

“Life Support System”

Brainstem


the oldest part and central core of the brain, beginning
where the spinal cord swells as it enters the skull
responsible for automatic survival functions

Medulla [muh-DUL-uh]
base of the brainstem
 controls heartbeat, blood pressure and breathing



Pons: Help coordinate movement, facial
expressions
Connects hindbrain with mid & forebrain
Cerebellum

Cerebellum [sehruh-BELL-um]
the “little brain”
attached to the rear
of the brainstem
 coordinate voluntary
movement and
balance (fine muscle
movements)

Cerebellum
Reticular Formation (Midbrain)

Reticular Formation

a nerve network in the brainstem that plays
an important role in controlling arousal and
sleep!
Explain the significance of the next
slide…
The Brain
The Forebrain (Thought and Reason)

Thalamus [THAL-uh-muss]


the brain’s sensory switchboard, located on top of the
brainstem (all but smell)
it directs messages to the sensory receiving areas in the
cortex and transmits replies to the cerebellum and
medulla
The Limbic System

Limbic System
a doughnut-shaped system of neural
structures
 at border of the brainstem and cerebral
hemispheres
 associated with emotions: fear and
aggression, drives such as hunger and sex
 includes the hippocampus, amygdala, and
hypothalamus.

The Limbic System
The Limbic System

Amygdala [ah-MIG-dah-la]

two almond-shaped neural clusters that are
components of the limbic system and are linked to
emotion (fear and aggression)
Hippocampus

Memory (more to come later…)

Hypothalamus

neural structure / below
(hypo) the thalamus;
Basic Drives:




hunger
thirst
body temperature
Sex drive (libido)
helps govern the
endocrine system via the
pituitary gland
 is linked to emotion

The Limbic System

Electrode
implanted in
reward
center
Hemispheres of the Brain


Left:
 Language and logic
Right:
 Spatial, creative
Why do most strokes affect the right
side of the body?

Most strokes occur in the left hemisphere
The Cerebral Cortex
(Thin layer of densely packed neurons: .0039-inch)

Cerebral Cortex
intricate fabric of interconnected neural cells
that covers the cerebral hemispheres (20 billion
nerve cells!)
 body’s ultimate control and information
processing center
 The larger the cortex, more adaptability,
capacity for learning
 Wrinkles = fissures (3 sq ft w/o them!)
 *Perceiving, thinking, speaking*


Glial Cells


cells in the nervous system that support,
nourish, and protect neurons
Aka neuron nannies or glue cells
The Cerebral Cortex
(Each hemisphere has 4
lobes)

Frontal Lobes


Parietal Lobes


include the sensory cortex (sensory center/ senses)
Occipital Lobes


involved in speaking and muscle movements:
judgement, logic (abstract thought, emotional control)
Vision: receive visual information from the opposite
visual field
Temporal Lobes

Hearing, or auditory areas
The Cerebral Cortex
The Cerebral Cortex

Motor Cortex

at the rear of the frontal lobes / controls
voluntary movements

What parts of body occupy most cortical space?


Fingers and mouth (require most precise control)
Sensory Cortex
at the front of the parietal lobes / registers
and processes body sensations
 The more sensitive the body region, the more
area occupied in the sensory cortex

The Cerebral Cortex
The Cerebral Cortex

Functional MRI
scan shows the
visual cortex
activated as the
subject looks at
faces
Visual and Auditory
Cortex
Association Areas




More intelligent animals have increased “uncommitted” or association
areas of the cortex
Association areas = 75% of cortex
Interprets, integrates and acts on info processed by sensory areas
Associates sensory input with stored memories (complex mystery)
Language and the Brain

Broca’s Area


Wernicke’s Area


Location: lower left frontal lobe / Role: directs
muscle movements making speech
Location: left temporal lobe / Role: language
comprehension and expression
Aphasia (language impairment)

usually caused by left hemisphere damage either to
Broca’s area (impairing speaking) or to Wernicke’s area
(impairing understanding)
Specialization and
Integration
Specialization and
Integration

Brain activity when hearing, seeing, and speaking
words
Brain Reorganization
 Plasticity
brain’s capacity to modify itself
 brain reorganizes / compensates after
damage, injury
 children have the most plasticity
 Example: blind and braille- one finger
used: sense of touch invades visual
cortex

Review Question
1.
When stroking the face of someone who’s
hand has been amputated, why did the subject
feel the sensation not only on his face, but also
on his amputated (“phantom”) fingers?
Answer: Hand area of the sensory cortex is no
longer used, thus fibers from other sensory
areas invade the space. (Note that the hand
area is between the face and arm regions of
the sensory cortex.)
In other words…. Plasticity!
Plasticity
Our Divided Brain
True or False:
1. Each hemisphere shares equally in
performing all functions of the body.
2. The two hemispheres can be isolated by
severing the corpus callosum.
3. Each hemisphere of the brain has a
“mind of its own.”
Our Divided Brain
Corpus callosum

Corpus
Callosum

large band of
neural fibers:
200,000,000!
connects the two
brain hemispheres
carries messages
between the
hemispheres
(billion pieces of
info / second!)


Our Divided Brain

The
information
highway from
the eye to the
brain
Split Brain
Isolate the 2 hemispheres
by cutting the connecting
fibers between them
(corpus callosum)
 To remedy uncontrollable
epileptic seizures


Testing the “split brain”
proves specific functions
of each hemisphere
The Split Brain Experiment
Dr. Gazzaniga- 1967
Stare at the Dot…..
he.art
1.
2.
Which word would the split-brain
patient verbalize seeing? Why?
Which word, when asked to point
with his left hand, would he report
seeing? Why?
Split Brain
Explain the following…
The Split brain
1. If this visual was
shown to the right
hemisphere of a split
brain patient, how
might the patient
identify the object?
The Split Brain
Interesting facts about the split brain:
 Subjects
can simultaneously draw different
figures with the left and right hand.
 When
the 2 hemispheres are at odds, the left
will rationalize reactions it doesn’t understand.
 The
hemispheres are an “odd couple”, each
with “a mind of its own.”
The Split Brain
Which hemisphere is more active with…
Simple requests
Right brain
Perceiving objects
Right brain
Decision making
(deliberative)
Left brain
Quick intuitive responses
Right brain
Recognizing faces
Right brain
Perceiving , expressing
emotion
Right brain
Hemispheric Differences in the Intact Brain



Hemispheric specialization = lateralization
Blood flow, glucose, brain waves detected between
hemispheres for perceptual tasks and speaking,
calculating tasks (EEG, PET, FMRI)
Sedative to artery to specific hemisphere: alters specific
functions of the body

If left hemisphere is sedated, what functions would be lost?


Language, right side of body limp
If sedative to right hemisphere?

Difficulty identifying themselves in altered photo, left side limp
Questions to consider….
1. If a word is flashed to your right hemisphere
(through your left visual field), why does it
take you slightly longer to state what you see
than it would if flashed to your left
hemisphere?

Process time through the corpus callosum
Which hemisphere would a deaf person use for
sign language?
right (visual / spatial) or left (language)?
2.
•
Left: to the brain, language is language
Handedness

What percentage of humans are right handed?


What ultimately makes you right or left handed?


90%
Genetics? Pre-natal? Social-Cultural?
What expressions can you think of that
discriminate against “lefties?”

Right on / right hand man / righteous / right mind -out in left field / left-handed compliment
Lefties tend to be…..
Musicians
Mathematicians
Professional baseball / cricket players
Architects
artists
Disappearing Southpaws

The percentage of left-handers decreases sharply in
samples of older people (adapted from Coren, 1993).
Percentage of 14%
left-handedness
12
The percentage of
lefties sharply
declines with age
10
8
6
4
2
0
10
20
30
40
50
Age in years
60
70
80
90
Brain Structures and their
Functions