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- How Neurons Communicate
- Neurons are communication specialists in our brain and spinal cord; they
use an electrochemical communication process.
- An electrical impulse (called the action potential) travels down to the
bottom of the axon where synaptic vesicles open and release chemicals
called neurotransmitters that travel across a synaptic gap and fit into
slots (receptors) like a key in a lock.
- After firing, the sending neuron reabsorbs excess
neurotransmitters (process called reuptake)
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- Neurotransmitters - chemical messengers that exist in brain, spinal cord,
peripheral nerves, some glands.
- They play a role in mood, memory, and psychological well-being.
- SEE TABLE
- Acetylcholine - chemical in every junction between a motor
neuron and a muscle.
- Botulin, a poison that can form in improperly canned
food, causes paralysis by blocking ACh release from the
sending neuron.
- Injections of botulin (Botox) smooth wrinkles by
paralyzing underlying facial muscles.
- Dopamine – excess linked to schizophrenia; undersupply linked
to Parkinson’s disease.
- Serotonin - role in depression (undersupply).
- Endorphins (endogenous morphine) - alleviate pain and may
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produce pleasure.
- Levels increase in response to pain, fear, or vigorous
exercise.
- May be involved in producing "runner's high".
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- Drugs Influence us by altering our neurotransmitters
- Cocaine blocks reuptake of dopamine, norepinephrine, and serotonin, producing
euphoria.
- When cocaine level drops, the absence of these neurotransmitters produces a
crash.
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- In this presentation, we’ll take a look at some different parts of our brain and
examine what they do.
- Limbic System
- Borders the brainstem and the cerebral hemispheres
- Amygdala - two almond-shaped neural clusters that influence aggression
and fear.
- Lesioning this part of the brain decreases aggression in animals.
- Electrically stimulating this area creates attack responses (or fear
responses depending on area stimulated).
- Hypothalamus - small structure below thalamus
- Involved in regulating hunger, thirst, emotion, sex drive
- Also thought to contain "reward centers" because animals will
feverishly engage in behavior that results in electrical stimulation
of this area.
- e.g., rat press bar in cage.
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- Hippocampus - compares sensory messages with learned expectations
- "Gateway to Memory" - involved in storing new information for
future use.
- e.g., A man by the name of Clive Wearing is a fascinating
example of what can happen to a person when their hippocampus
is damaged due to a disease.
- Clive retained his old memories of his wife and music, but he
could not retain any new information for more than a few seconds.
- Click on the link to watch the video
http://www.learner.org/vod/vod_window.html?pid=1617
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- CEREBRAL CORTEX (At top of brain; has folds).
- Structure of the Cortex (four regions, or lobes)
- Occipital Lobes - lower back portion; Contain Visual Cortex where visual
signals are processed.
- SHOW
- Parietal Lobes - Top portion
- Contain Somatosensory Cortex
- SHOW
- Receives info about pressure, pain, touch, temperature.
- Also allows us to know position of various parts of our body
(e.g., arms, legs).
- Temporal Lobes - Sides of brain, above ears
- Involved in memory, perception, emotion, and language comprehension
- Contain auditory cortex (processes sounds).
- SHOW
- Frontal Lobes - Front of brain
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- Involved in ability to make plans, creative thinking, taking initiative.
- Contain Motor Cortex (produce voluntary movement)
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