Download The Brain

SURVEY OF MODERN
PSYCHOLOGY
The Brain
We will discuss:
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The parts of the brain and what they do
Neurotransmitters
The effects of various drugs on the brain and
neurotransmitters
Some general notes about the brain
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Bilaterally symmetrical along the longitudinal fissure
The left and right side communicate via the
corpus callosum
Contra lateral control – the left side of the
brain controls the right side of the
body and vice versa
The parts of the brain
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Going from the back of the brain towards the front,
functions are more advanced
Hindbrain
Midbrain
Forebrain
Hindbrain
Hindbrain
Cerebellum
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Balance
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Damage (permanent or chemical) causes a wide staggering gait
Performance and timing of skilled movements
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Damage here causes tremors during movement and an inability to perform rapidly
alternating movements
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Ex. This would interfere with a skill such as typing
Pons
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Regulating the brain’s level of attentiveness
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Initiating sleep and dreaming
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Integrates movements of and sensations from the facial muscles, eyes, tongue, and ears
Medulla
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Controls basic biological functions
 Cardiovascular and respiratory systems
 Reflexes (e.g. coughing, swallowing, sneezing)
 Maintains balance by controlling head orientation and limb positions with respect
to gravity)
Midbrain (Mesencephalon)
Midbrain (Mesencephalon)
•Includes the Tectum and Tegmentum
•Tracking moving stimuli (visual and auditory)
•Controls eye movements
•Coordinates simple movements (controlled by the hindbrain) to form more
complicated wholes
•Damage here makes the organism unable to perform purposeful behaviors
•E.g., an animal can move and chew, but will not initiate a search for food
when it is starving
Forebrain
Forebrain
Parts:
 Cerebral cortex
 Limbic system
 Thalamus
 Hypothalamus
Forebrain
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Thalamus
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Receives sensory information and conveys it to the relevant structures
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Hypothalamus
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Controls the autonomic nervous system, endocrine system, and major biological drives
Basal ganglia
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Control of movement
Damage/degeneration here causes Parkinson’s disease
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E.g., vision and other senses, balancing information for movement
Weakness, tremors, rigidity of limbs, poor balance, difficulty in initiating movements
Includes the hippocampus and amygdala
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Learning
Memory
Storing new information into long term memory
Some regions are involved in emotions – feeling and expressing emotion, emotional memories, and
recognition of signs of other people’s emotions
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Stimulation generally produces feelings of anxiety and/or rage
Cerebral Cortex
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Cerebral Cortex
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Frontal lobe
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Parietal lobe
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Senses (touch, pain, temperature)
Temporal lobe
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Memory, strategy formation, response inhibition
Conscious thought
Hearing
Occipital lobe
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Vision
The frontal lobe is largely linked to personality
Much of what we know comes from instances of brain damage or injury
Phineas Gage
In an accident in the mid 1800s, a large steel rod
went through his head
He survived, but friends said that there were
major changes in his personality and was “no
longer Gage”
 In general, injury to the frontal lobe results in:
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Lack of spontaneity
Few facial expressions and gestures
Limited and non-fluent speech
Strategy formation
Lack of response inhibition

The person does not understand rules and therefore
has difficulty following rules
•The Hemispheres
•There is a lot of popular theory/cultural belief that the left
and right hemispheres serve vastly different functions.
•In reality, both hemispheres do play some part in almost all
areas.
•Most likely, one side is simply more effective and efficient in
performing specific tasks.
•The division of labor is described as seen in right handed
people.
Visual System
Left Hemisphere
 Letters
 Words
Right Hemisphere
 Complex geometric
patterns
 Faces
Auditory System
Left Hemisphere
 Language related
sounds
Right Hemisphere
• Non-language,
environmental sounds
• Music
Somatosensory System
Left Hemisphere
 Unknown
Right Hemisphere
• Tactile recognition of
complex patterns
• E.g., Braille
Movement
Left Hemisphere
 Complex voluntary
movement
Right Hemisphere
• Movements in spatial
patterns
Memory
Left Hemisphere
 Verbal memory
Right Hemisphere
• Nonverbal memory
Language
Left Hemisphere
 Speech
 Reading
 Writing
 Arithmetic
Right Hemisphere
• Prosody
• Narrative
• Inference
Spatial Processes
Left Hemisphere
 Unknown
Right Hemisphere
• Geometry
• Sense of direction
• Mental rotation of
shapes
Final Notes on Hemispheres
The left and right hemispheres are joined by the corpus callosum.
In some severe cases of epilepsy, surgery is performed to cut the corpus callosum.
1981: the Nobel Prize was given to Roger Sperry for his research on “split brains”
A participant was prevented from seeing the object and given a pencil in their left
hand
The nerve impulse therefore reached the right hemisphere, but not the left
The participant could generally demonstrate what the pencil should be used for
with motions, but could not name the object
They could only name the object if it was placed in the right hand.
When shown a stimulus is shown on the right side (processed by the left hemisphere)
such as words, it is processed faster than if the same was shown on the left side. The
right hemisphere needs to send the image to the left side for processing.
Brain Damage
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Apraxia
 Disturbances
in movement
 Lesions in the frontal lobe; disconnect in primary and
nonprimary motor areas
 Disturbances in initiation or organization of voluntary
actions
 Ex.
Unable to wave
 Ex. When trying to bake, a person might try to repeatedly
break the same egg, or put a measuring spoon in a bowl as
well as the ingredient
Brain Damage
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Agnosia
 Inability
to identify familiar objects using a particular
sense
 Visual
agnosia – able to identify a car key by touch, but not
by appearance
 Able to recognize parts but not a whole
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Prosopognosia – inability to identify faces
 This
might be the inability to recognize a face as a
face
Brain Damage
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Aphasia
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Disturbances in language
Caused by damage by lesions, usually in the left hemisphere
Nonfluent aphasia
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Inability to produce speech, but comprehending what is said
Fluent aphasia
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Inability to comprehend what is said
Speech is made of filler words, with no information
People who can hear sometimes learn Sign Language to communicate
HOWEVER
Deaf people who suffer the same brain damage experience the same
difficulties in communication as hearing people with aphasia
Neurons
Parts of a neuron:
 Dendrites
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Receive impulses from other neurons
Cell body
Axon
Synapse (the space between cells)
Communication occurs across synapses
via neurotransmitters
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Neurotransmitters are usually
ejected, brought back into axons,
and then reused
Lock and key model: the transmitter
will only have an effect if it fits into
the receptor molecules
Neurotransmitters
The ones we will discuss are:
 Dopamine
 Serotonin
 Norepinephrine
 Acetylcholine
 GABA
 Glutamate
 Endorphins
Dopamine
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Normal function
Produces sensations of pleasure and reward
 Used by the central nervous system (CNS) neurons involved
in voluntary movement
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Problems associated with imbalance
Schizophrenia
 Parkinson’s disease
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Substances that affect the action of this neurotransmitter
Cocaine
 Amphetamine
 Alcohol
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Serotonin
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Normal function
 Regulates
sleep and dreaming, mood, pain, aggression,
appetite, and sexual behavior
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Problems associated with imbalance
 Depression
 Some
anxiety disorders
 Obsessive compulsive disorder
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Substances that affect the action of this
neurotransmitter
 Hallucinogenics
Norepinephrine
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Normal function
Used by neurons in the automatic nervous system and by
neurons in almost every region of the brain
 Controls heart rate, sleep, stress, sexual responsiveness,
vigilance, and appetite
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Problems associated with imbalance
High blood pressure
 Depression
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Substances that affect the action of this neurotransmitter
Tricyclic antidepressants
 Beta blockers
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Acetylcholine
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Normal function
The primary neurotransmitter used by neurons carrying
messages form the CNS
 Involved in some kinds of learning and memory
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Problems associated with imbalance
Some muscular disorders
 Alzheimer’s disease
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Substances that affect the action of this neurotransmitter
Nicotine
 Black widow spider venom
 Botulism toxin
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GABA
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Normal function
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The most prevalent inhibitory neurotransmitter in neurons of
the CNS
Problems associated with imbalance
Anxiety
 Epilepsy
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Substances that affect the action of this neurotransmitter
Barbiturates
 “Minor” tranquilizers (ex. valium)
 Alcohol
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Glutamate
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Normal function
 The
primary excitatory neurotransmitter in the CNS
 Involved in learning and memory
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Problems associated with imbalance
 Release
of excessive glutamate causes brain damage
after strokes
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Substances that affect the action of this
neurotransmitter
 PCP
(angel dust)
Endorphins
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Normal function
 Pleasurable
sensations
 Control of pain
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Problems associated with imbalance
 Lowered
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levels resulting from opiate addiction
Substances that affect the action of this
neurotransmitter
 Opiates
(opium, heroin, morphine, methadone)
Drugs
Drugs act on synapses (the spaces between neurons)
and affect the response to neurotransmitters
 Agonists facilitate effects
 Antagonists inhibit effects
 Dependence and addiction are characterized by
tolerance and withdrawal
Drugs
Physical vs. psychological dependence
 Physical addiction is often defined by the physiological
effects that happen when a person stops using a drug
 Psychological dependence involves the emotional feeling of
wanting the drug either to produce pleasure or avoid
discomfort
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Psychological addiction tends to be more difficult to overcome
than physical addiction
Positive reinforcement – if it feels good, keep doing it!
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Withdrawal is the opposite of whatever the effects of the drug
are
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(E.g., withdrawal from an opiate causes agitation)
Types of Drugs and their Effects
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Opiates
Stimulants
Nicotine
Alcohol and Barbiturates
Cannabis/THC
Opiates
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Naturally occurring opiates in the brain block pain
Cause analgesia, hypothermia, sedation,
reinforcement
Act on GABA and dopamine
Opiate blockers may be used to treat addiction (no
effect, therefore no reinforcement)
Stimulants
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Dopamine agonists
 Stimulate
the release of dopamine and inhibit the
reuptake
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Euphoric, active, and talkative
 Hallucinations,
paranoia, mood disturbances, repetitive
behavior
 Similar to schizophrenia
Nicotine
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Dopamine and acetylcholine agonists
Often harder to quit than “hard” drugs
Withdrawal includes anxiety, restlessness, insomnia,
inability to concentrate
Nicotine antagonists can also reduce cocaine
cravings
Alcohol and Barbiturates
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Dopamine and GABA agonists
Small doses produce mild euphoria and inhibits anxiety – stops the
punishing effects of aversive stimuli
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Alcohol:
Withdrawal can be fatal
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Ex. if an animal is given shocks when it performs a particular action, it will stop.
If given alcohol, it will not learn and keeps performing the response
Convulsions and seizures
Chronic alcoholism can lead to Korsakoff’s Syndrome
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This is caused by a vitamin deficiency – frequent alcohol use can block the absorption
of some vitamins
Permanent anterograde amnesia (inability to form new memories, but still having
old ones)
Confabulation – making up memories
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Can have elements of reality or be completely imaginary
Cannabis/THC
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Cannabis:
 Dopamine
agonist
 Particularly affects the hippocampus, causing memory
problems
 Long term use can cause inattentiveness, impaired
memory, reduced ability to multitask