Transcript Biological Psychology Modules 3 & 4

Biological Psychology
Biological Roots of Behavior
How the Brain Governs Behavior
Neurotransmitters
“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
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
The Whole Brain Atlas
What the Brain Controls
The Lobes of the Brain
A Positron Emission Tomography Scanner
(PET)
So we can understand how
people get……..
Murderous mind?
A PET scan
reveals less
activity in the
prefrontal cortex
of a convicted
killer (right)
than in that of a
nonviolent
control.
A Pet Scan of a Depressed Patient
A PET Scan of a Schizophrenic Patient
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)
Neurons
More Neurons
And just one more!!
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