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Biological Psychology
Neural and Hormonal Systems – Module 3
How the Brain Governs Behavior – Module 4
Neurotransmitters – Module 3
General Psych 1
February 8-10, 2005
Classes #5-6
“So why do we have to study
biology in a psych class?”

Let me use Phineas
Gage to help
answer this
question…
“He was no longer Gage…”

Several different
angles of where
the rod passed
through his skull
There is a Phineas Gage display in the Warren
Medical Museum at Harvard University

This is what went through his brain (see
below)…
Biological Roots of Behavior
Franz Gall (1758-1828) – Austrian
physicist who invented phrenology
 He felt that bumps on the skull could
reveal our mental abilities and character
traits.
 Introduced as being scientific but its use
was exploited by quacks on gullible
individuals

Biological Roots of Behavior
Became similar to that of astrology,
palm-reading and tarot
 Although, ill-fated theory was laughed at
by scientific community of that day – it
may have had some validity
 Localization of brain functions somehow
hit the mark

The Nervous System

Electrochemical communication system that
enables us to think, feel, and behave
 Complex beyond comprehension
 Although, human brains are more complex
our nervous systems and those of animals
operate in a similar fashion – advantage of
this is experimentation
Major Components

Neurons:
– Rapidly respond to signals and quickly
send signals of their own

Glial cells:
– Help neurons to communicate, keep
chemical environment stable, secrete
chemicals to help restore damage, and
respond to signals from neurons – enable
neurons to function
Axons

Function:
– Carries signals away from the cell body
– Pass information along to other nuerons, or
to muscles or glands

Type of Signal Carried:
– The action potential, an all-or-nothing
electrochemical signal that shoots down
the axon to vesicles at the tip of the axon,
releasing neurotransmitters
Synapse
Very small gap between neurons
 For communication to occur between
cells, the signal must be transferred
across this gap
 Function:

– Provides an area for the transfer of signals
between neurons, usually between axon
and dendrite
Dendrite

Function:
– Detects and carries signals to the cell body

Type of Signal Carried:
– The postsynaptic potential, which is an
electrochemical signal moving toward the
cell body
Receptors

Function:
– Proteins on the cell membrane that receive
chemical signals

Type of Signal Carried:
– Recognizes certain neurotransmitters, thus
allowing it to begin a postsynaptic potential
in the dendrite
Okay, so how do neurons actually
transmit information?
A neuron:

–
–
–
Receives signals form other neurons
through its branching dendrites and cell
body
Then combines these signals in the cell
body
And then transmits an electrical
impulse down its axon
Transmitting information…

The impulse is called the action potential
which is a brief electrical charge that travels
down the axon like a line of dominoes falling,
each one tripping up the next
 This is real electricity as a handful of neurons
produce enough power to light up a flashlight
 When electrical signals reach the end of the
axon, they stimulate the release of chemical
messengers – neurotransmitters
Neurotransmitters

Function:
– A chemical released by one cell that binds
to the receptors on another cell

Type of Signal Carried:
– A chemical message telling the next cell to
fire or not to fire its own action potential
The Nervous System

Allows researchers to study simple
animals such as squids and sea slugs
to help us better understand the
organization of our own brains
Divisions of the Nervous System

Consists of two systems
– Central Nervous System
• Brain and spinal cord
– Peripheral Nervous System
• Which connects the CNS to the rest of
the body
Organization of the Nervous System
Peripheral Nervous System

Two components:
– Somatic Nervous System
• Transmits sensory input to the CNS from
the outside world and directs motor
output
– Autonomic Nervous System
• Controls glands and muscles of our
internal organs – “automatic pilot”
Autonomic Nervous System

Dual system:
– Sympathetic Nervous System
• Arouses the body
– Parasympathetic Nervous System
• Calms us down
Neurons

Nerve cells (building blocks) –
essentially identical to animals
– Small samples of brain tissue from a
person and a monkey are basically
indistinguishable
Endocrine System: Taking the slow lane
Unlike the speedy nervous system
which zips messages from eyes to brain
to hand in a fraction of a second,
endocrine messages use the slow lane
 May take several seconds or more as
bloodstream carries a hormone from an
endocrine gland to its target tissue

Endocrine System
Hormones are chemical messengers
 Influence all aspects of our lives –
growth, metabolism, reproduction,
moods, etc.
 Strives for homeostasis (balance) by
responding to stress, exertion, internal
thoughts, etc.

The Brain

Studying the brain:
– Clinical observations
– Manipulating the brain
How does the brain govern
behavior?
3 Principle layers of the brain:
(1) Brainstem
(2) Limbic System

• Hippocampus
• Amygdala
• Hypothalamus
(3) Cerebral Cortex
Brainstem (or Hindbrain)

The brain’s innermost region…
– Begins where the spinal cord enters the
skull and swells slightly forming the
medulla
– Towards the rear of the brainstem is the
cerebellum – this is linked to memory and
its major function is muscular control
Limbic System

Hippocampus
– This structure plays a key role in allowing
us to store new information
– Problems here may cause Alzheimer's –
these individuals have trouble processing
declarative memories
– Milner (1968): the classic case of H.M.
Limbic System

Amygdala
– Emotional control center of the brain –
major influence on aggression and fear
– Emotional memories as well
– Alzheimer’s ???
 Kluver and Bucy (1939)
 Demasio (1994)
Limbic System

Hypothalamus
– Major influence on hunger, thirst, body
temperature, and sexual behavior
• Olds and Milner (1954)
Cerebral Cortex

Makes us distinctively human – much higher
developed than in animals
– Motor Cortex – involved in the conscious initiation
of voluntary movements in specific parts of the
body including hand, knee, foot and head

Fritsch and Hitzig (1870)
 Delgado (1969a)
 Delgado (1969b)
 Penfield (1975)
Cerebral Cortex

Sensory Cortex – receives information from
our senses
– Visual cortex
• visual info
– Auditory cortex
• auditory info
– Somatosensory cortex
• info from skin
 Association cortex
– involved in complex cognitive tasks associating
words with images
• Broca’s area (aphasia)
• Wernicke’s area (aphasia)
Neurotransmitters

Neurotransmitters are chemicals made by
neurons and used by them to transmit signals
to the other neurons
 A chemical message telling the next cell to
fire or not to fire its own action potential
 More than 200 in our body all with different
functions
 Lets briefly discuss some of the most
important ones…
Serotonin
Facilitates a relaxed, sleepy feeling
 Tryptophan which is an amino acid
found in dairy products and turkey is
converted into serotonin in the body
 So, insomnia sufferers may be smart to
listen to grandmother’s suggestion to
drink a warm glass of milk before going
to bed

Some Illnesses Associated With Serotonin
Too low levels in depression and anxiety
sufferers
 Obesity may also be associated with
low levels
 Linked to aggression as well -- low
levels in the brains of suicide victims

Dopamine




High levels lead to pleasure
– Makes person feel happy and active
Dopamine raises the body's temperature
and increases metabolic rate
Gives you euphoric feelings and allows you
to be active
Drug and alcohol abuse will block dopamine
receptors and therefore a person needs to
take more to get the same effect
Illnesses Associated With Dopamine
Parkinson’s Disease – too low levels
 Schizophrenia – too high levels
 Tourette’s disorder – too high levels
 Huntington’s disease – too high levels

Norepinephrine
Plays a role in attention and arousal
 Used by sympathetic nervous system to
prepare us for action

Illnesses Associated With Norepinephrine

Depression
– chronic stress depletes this
neurotransmitter and can lead to
depression

Note:
– Aerobic Exercise is found to protect the
brain from this depletion – so go out and
run a mile or two if your down in the dumps
Epinephrine

Involved in energy and glucose
metabolism
Illnesses Associated With Epinephrine

Depression – too low levels
Acetylcholine
Involved in voluntary movement,
learning, memory, and sleep
 Helps parasympathetic nervous system
to slow our heart rate

Illnesses Associated With Acetylcholine
Alzheimer’s disease – too low levels
 Note:

– Unfortunately, drugs used to increase
acetylcholine to help restore normal levels
appear to have small effects on improving
memory
GABA
Inhibits excitation and anxiety
 Appears directly related to anxiety
reduction

Illnesses Associated With GABA


Anxiety disorders – too low levels
Huntington’s Disease – too low levels
– GABA systems aren’t working and this allows
dopamine systems to run wild
– Huntington's disease is a hereditary disorder
characterized by memory loss, abnormal
movement and premature death
• It affects 1 in 10,000 people, and children with an
affected parent have a 50 percent chance of
developing the disease

Epilepsy – too low levels
Glutamate
Main excitatory neurotransmitter in the
brain
 Very important in learning and memory

Illnesses Associated With Glutamate
 Alzheimer’s
disease – too low levels in
hippocampus
 Strokes – too high levels can cause
neurons to die
 ALS (Lou Gehrig’s Disease) – causes
death in neurons in the spinal cord and
brainstem
Endorphins
Involved in pain reduction and pleasure
 They enhance the release of dopamine
 These natural opiates are released in
response to pain and vigorous exercise

Illnesses Associated With Endorphins

Use of artificial opiates can cause body
to stop manufacturing its own – this can
lead to drug addiction