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1 The Nervous System and the Brain- The Big Picture Neuron The Peripheral Nervous System The Central Nervous System and the Brain The Endocrine System Putting it all together - the example of hunger

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Page 1: 1 The Nervous System and the Brain- The Big Picture Neuron The Peripheral Nervous System The Central Nervous System and the Brain The Endocrine System

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The Nervous System and the Brain-The Big Picture

• Neuron• The Peripheral Nervous System• The Central Nervous System and the

Brain• The Endocrine System• Putting it all together - the example of

hunger

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The Neuron

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How Impulses Travel Down the Neuron

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The Synapse

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Neurotransmitters

• Dopamine - involved in movement, attention, emotion. Deficiencies of it in Parkinson’s Disease. Excesses of it in Schizophrenia.

• Serotonin - involved in mood, hunger, sleep, arousal. Deficiencies associated with Depression.

• Norepinephrine - involved in alertness and arousal. Deficiencies associated with Depression.

• Acetylcholine - involved in muscle movement, learning and memory. Damage to neurons that produces it, part of Alzheimer’s Disease.

• Endorphins - involved in pain regulation. Heroine and morphine mimic this neurotransmitter.

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How Drugs Affect Neurotransmitters

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Divisions of the Nervous System

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The Peripheral Nervous System

• Somatic Nervous System - Controls voluntary muscles movement

• Autonomic Nervous System - Controls glands and muscles related to our organs. Although possible to override by conscious thought, for the most part these reactions occur spontaneously.

• Sympathetic Nervous System - Arouses the person to get ready for fight or flight.

• Parasympathetic Nervous System - Calms and relaxes the person. Conserves energy.

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The Central Nervous System -The Big Picture

• Spinal Cord and the Brain• Spinal Cord carries information and

controls some reflexes• The Brain does almost all processing -

3 areas you need to know about• The Brainstem - controls many basic

functions• The Lymbic System - control

motivation and very important in memory

• The Cerebral Cortex - complex processing of information

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How the Spinal Cord Controls Reflexes

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The Brainstem

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The Brainstem (cont.)

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The Lymbic System

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The Cerebral Cortex -Basic Divisions

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Cerebral Cortex Functional Divisions -

Movement and Sense of Touch

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Cerebral Cortex Functional Divisions -

Hearing and Vision

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Cerebral Cortex Functional Divisions-

Left and Right Sides of the Brain

• Corpus Callosum - separates the two sides of the brain and when severed they function differently for at least awhile.

• People who have the Corpus Callosum severed are call split brain patients.

• Left side is more verbal• Right side is better at visual

processing

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The Endocrine System

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Putting it All Together-The Case of Hunger

• When we don’t eat for awhile what makes us hungry?• Stomach contractions carry hunger

signal through the peripheral nervous system to the hypothalmus

• Blood sugar levels as interpreted and controlled by the liver and pancreas send message to the hypothalmus.

• The lateral hypothalmus is stimulated and probably and releases the hormone orexin which heightens hunger.

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Picture of the Brain of a Hungry Person

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Putting it All Together-The Case of Hunger (cont.)

• When we eat what makes us no longer feel hungry?• Our stomach expands and this message

is transmitted to the hypothalmus.• Blood sugar levels as interpreted and

controlled by the liver and pancreas send message of higher levels to the hypothalmus. Insulin is also released.

• The ventromedial hypothalmus is stimulated and which leads to the feeling of satiation and helps stop the eating.

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Damage to the Hypothalmus and Fat and Skinny Rats

• If there is a lesion to the lateral hypothalmus then rats basically starve themselves to death and virtually eat nothing. They also seem lethargic and depressed. This area is probably also related to pleasure.

• But if the ventromedial hypothalmus is damaged then rats basically will never stop eating and they get very fat.

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Overarching Principles

• There is a lot of specificity or specialization in function

• Structures of the brain and the various systems work together in coordinated, overlapping, and redundant systems.

• Despite all this specificity and complexity the brain has quite a bit of plasticity. This means if an area is damaged other areas can take over-particularly among young children.

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Coordinated Brain Activity -The Big Picture

• The Senses• Vision• Hearing• The Others - Taste, Smell, Touch,

Pain and Balance• Language Processing in the Brain• Your Brain When You’re Asleep

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The Parts of the Eye

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A Closer Look at the Retina

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From the Eye to the Cortex

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Feature Detection

• In the cortex individual cells respond to lines at various angles

• These cells converge to create our perception of what we see

• Higher level cells provide even more interpretation

• All of this happens with a lot of parallel processing of information.

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Colour Vision

• Young-Helmholtz Trichromatic Theory -• Three primary colors: red, green,

blue • These are mixed to make all the

colors• Consistent with people who are

colorblind• Opponent-Process Theory - • Three opponent color pairs:

black/white, red/green, blue/yellow• Explains afterimage effect

• Both are probably true

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The Parts of the Ear

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A Closer Look at the Cochlea

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Pitch Perception

• Place Theory - It is the place on the basilar membrane that is stimulated that creates the pitch

• Frequency Theory - It is the speed of the ‘waves’ in the cochlea that determines the pitch

• Both seem to be true • Place theory explains high pitches• Frequency theory explains low

pitches.

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Other Senses - Taste, Smell, Touch, Pain, and

Balance

• Taste - Four basic sensations • Sweet• Sour• Salty• Bitter

• More do occur -- what is spicy?• These sensation are a created by

chemical reactions on your taste buds• Taste is heavily influenced by smell -

this is called sensory interaction

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Smell

• Smell is also a chemical sense - it is chemical reactions in the olfactory membrane that create smells

• We still do not understand exactly how receptors in the olfactory membrane work

• Odors can powerfully evoke memories• Odors can powerfully evoke emotions

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Smell and the Brain

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Sense of Touch

• There are specialized nerve endings in our skin, but these do not seem to have a relationship with what we feel

• Our skin is sensitive to pressure, warmth, cold, and pain

• These sensitivities give rise to quite varied sensations• Tickle• Hot: warm + cold = hot• Wet: cold + pressure

• We don’t know much about these sensation

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Pain

• We know much more about pain - but the more we know the more difficult it is to understand

• No definable area of the brain, but the brain is definitely involved

• Gate-Control Theory - Spinal chord has a neurological gate that either blocks pain signals or allows them to travel to the brain.• Distraction can close the gate• Endorphins can close the gate

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Balance Receptors in the Ear

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Balance

• You probably have never thought about balance as a sense, but think back to when you have ridden on a merry-go-round or a rollercoaster.

• The sense of feeling balanced (or negatively of feeling dizzy and disoriented) is called the kinesthetic sense.

• There are two ways we perceive this sense.• Our joints and muscles tell us the

position of our body• The semi-circular canals in the ears tell

us the vestibular sense or the position our our head

• Together these allow us to perceive balance.

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Focus on University of Waterloo Research Synaesthesia

• Synaesthesia is the blending of sensations

• There is a group of researchers at U of W who study this phenomenon

• One of the more common examples of synaesthesia is digit-colour synaesthesia

• Let’s look at a UW experiment demonstrating this phenomenon

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How a Synaesthete Describes the Experience

“It is difficult to explain . . . I see what you see. I know the numbers are in black, but as soon as I recognize them I automatically see in my mind a particular colour . . . As soon as I recognize the form as 7 it has to be yellow.”

C (1999)

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An Example of What this Might Look Like

4 44 4

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Outline of a UW Experiment

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Congruent

Incongruent

%

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Results of the Experiment

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Coordination of Language in the Brain -

How Do we Read Outloud

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Brain Coordination While We Sleep -

The Active Sleeping Brain

• The activity in our brain in remarkably varied while we sleep

• There are five stages of sleep defined by brain activity that occur when we sleep

• REM sleep is when we dream

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The Sleep Cycle

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Why Do We Sleep and Dream?

• We know when we don’t sleep we feel terrible

• When we don’t sleep we are not alert and were more likely to get in accidents

• But this doesn’t answer why?• Perhaps it will help to look at dreaming

- Why do we dream?• Freud said wish fulfillment• Modern theory is called activation-

synthesis • We probably need dreams for memory

consolidation and cognitive development

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Sleep Throughout the Lifetime