Neuroscience, Genetics and Behavior

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Neuroscience, Genetics and Behavior
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True or False?

• Basic biological processes underlie all human
  behavior.
• Various branches of psychology rest on this
  foundation.

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Biological Psychology(or Psychobiology)

• The most significant transformation in modern
  psychology
• AKA Biopsychologists, behavioral neuroscientists,
  behavior geneticists, physiological
  psychologists, neuropsychologists

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An intro to neuroscienceExplain the following

1. Modern psychology views each individual as a
   biopsychosocial system.
2. Everything psychological is simultaneously
   biological.
3. The mind is what the brain does..
4. A brain simple enough to be understood is too
   simple to produce a mind able to understand it.

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Introducing the neuron

• Simple definition
• a nerve cell
• The incredible neuron.
• basic unit of information processing and the
  building block of the brain. (and nervous
  system)
• Working together with other neurons and cells
  throughout the body, it allows us to think, feel,
  move and breathe.

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A vastly complex system

• Facts about neurons
• 100 billion neurons in the human brain and CNS!
  (and 400 trillion synapses!)
• A grain of sand-size part of the human brain
  holds 100,000 neurons!

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Neural Structure

• Dendrite (receives impulse)
• Branching extensions of a neuron / receive
  messages / conduct impulses toward the cell body
• Axon (transmits impulse)
• extension of a neuron, ending in branching
  terminal fibers, through which messages are sent
  to other neurons or to muscles or glands
• Remember Axons speak, dendrites listen
• Myelin Sheath (speeds impulse)
• a layer of fatty cells segmentally encasing the
  fibers of many neurons
• Speeds transmission of neutral impulses

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Neural Structure

• So what happens when the myelin sheath begins to
  wear out?
• Alzheimer's (impedes transmissions affecting
  thought process)
• Multiple sclerosis interferes with muscle
  control (as message to muscles is impeded..)

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Neural Structure
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Neural Communication an electrochemical
process

• Neural communication is a conversation between
  cells that generates our thoughts, actions, moods
  and memory.

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Neural Communication

• Action Potential
• a neural impulse a brief electrical charge that
  travels down an axon
• Stimulated when neuron receives signals from
  sense receptors stimulated by heat, pressure or
  light
• generated by the movement of positively charged
  atoms in and out of
• channels in the axons membrane

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Neural CommunicationWhat one neuron tells
another neuron is simply how much it is excited.

• Each neuron has a threshold
• the level of stimulation required to
• trigger an action potential (or neural impulse)
• Threshold is determined by excitatory
  (accelerator) and inhibitory (brakes) triggers
  that determine the action potential (neural
  impulse)

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Neural Communication

• Neurons generate electricity from chemical events
  (like batteries)
• The chemistry to electricity process involves
  the exchange of ions
• Ions electrically charged atoms

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Ions

• Resting Potential
• Fluid inside a resting axon has negatively
  charged atoms
• Fluid outside the axon membrane has positively
  charge atoms
• Natural state of inside / outside ions resting
  potential
• Axons surface is selectively permeable (it
  decides what it allows in..)

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Reaching a Neurons Threshold

• When the neuron fires
• Axon opens gates (selectively permeable) and
  charged sodium ions flood the membrane
• sodium ions cause depolarization
• Depolarization causes reaction as axons pass the
  impulse down the chain (like dominoes)
• Opens and closes 100-1000 times /second!

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Reaching a Neurons Threshold

• Refractory Period
• Once impulse has been passed, the axon pumps
  ions back out of membrane, and thus recharges
• All or none response
• Increased stimulus does not increase the action
  potentials intensity (a gun either fires or
  doesnt)

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Neural Communication
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Neural Communication

• Synapse (Where the action is)
• gap between the axon tip of the sending neuron
  and the dendrite or cell body of the receiving
  neuron
• tiny gap at this junction is called the synaptic
  gap or cleft (less than a millionth of an inch!)
• Neurotransmitters
• chemical messengers that cross the synaptic gaps
  between neurons
• neurotransmitters bind to receptor sites (lock
  and key) on the receiving neuron, thereby
  influencing whether it will generate a neural
  impulse
• Thus ions passed on to new neuron exciting or
  inhibiting its readiness to fire..

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Neural Communication

• Reuptake
• Excess neurotransmitters are reabsorbed by the
  sending neuron

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Neural Communication
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Neurotransmitters

• About 75 have been discovered
• We will study 7-8

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Neurotransmitters(Take notes on last 2 listed)
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Neurotransmitters

• GABA
• Inhibitory neurotransmitter
• Undersupply seizures, tremors, insomnia

• Glutamate
• Excitatory neurotrasmitter
• Invovled in memory
• Too much migraines, seizures
• Excitotoxicity excite a neuron to death (glial
  cells help prevent)
• Chinese food- MSG (glutamate) headaches

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Neurotransmitters

• Acetylcholine ah-seat-el-KO-leen
• ACh
• triggers muscle contraction (movement, learning,
  memory)
• Undersupply Alzheirmers

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Neurotransmitters

• Endorphins en-DOR-fins
• morphine within
• natural, opiate-like neurotransmitters
• linked to pain control and to pleasure
• Runners high
• Opium, heroine addicts brain stops producing
  natural opiates, thus withdraws

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Neurotransmitters

• Norepinephrine
• Mood
• Too much mania / too little depression
• Imbalance bipolar disorder

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Neurotransmitters

• Serotonin
• Sleep, eating, mood
• Related to depression
• Prozac (anti-depressant drug) raises serotonin
  levels

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Neurotransmitters

• Dopamine
• Perceptual awareness, muscle control
• Too much Schizophrania (up to 6x more dopemine)
• A Beautiful Mind / The Soloist
• Too little Parkinsons Disease (tremors
  Muhammad Ali)

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Drugs Affect Neurotransmission

• Drugs can be used to affect communication at the
  synapse
• Agonists excite, or mimic the neurotransmittors /
  or block reuptake (drug addicts and withdraw)
• Antagonists block, or inhibit neurotransmitters
  signal (examplesBotox/ botulism blocks Ach)
• A complicated process Brain has blood-brain
  barrier that blocks out unwanted chemicals

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Neural Communication
Neurotransmitter molecule
Receiving cell membrane
Agonist mimics neurotransmitter
Antagonist blocks neurotransmitter
Receptor site on receiving neuron
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Neural Communication
Serotonin Pathways
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Remember

• Communication within the neuron is.
• Electrical
• Communication between neurons is.
• chemical

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Glial cells (Glia)

• Make up 90 of brains cells
• Protect, nourish neurons
• Current research suggests possible action
  potentials, debate as to role
• See p. 45 Alchemy of Mind

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An Alchemy of Mind

• Explain fully each of the following quotes from
  your reading.
• Neurons speak an elite pidgin neither chemical
  nor electrical but a lively buzz that joins the
  two, an electrochemical lingo all their own.
• It is important to realize that what one neuron
  tells another neuron is simply how much it is
  excited.
• It is a small liquid space, as is the air between
  two whispering lovers, yet so much life happens
  there. Each junction is a bazaar full of
  commerce, intrigue and possibility. In the brain,
  everything depends on almost nothing, a lively
  space.
• Coexisting as they must, both neurons and glia
  are dependable, dependent central to the brains
  social fabric and perpetual hum.

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The Nervous System

• Nervous System
• the bodys speedy, electrochemical communication
  system
• consists of all the nerve cells of the PNS and
  CNS
• Central Nervous System (CNS)
• the brain and spinal cord (encased in bone)
• Peripheral Nervous System (PNS)
• connect the central CNS to the rest of the
  bodys sense receptors

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The Nervous System
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The Autonomic Nervous System

• Autonomic Nervous System
• part of the PNS controls the glands and the
  muscles of the internal organs (involuntary)
• A Dual System
• Sympathetic Nervous System
• arouses the body, mobilizing its energy in
  stressful situations (Fight or flight, or
  sympathy in crisis)
• Parasympathetic Nervous System
• calms the body, conserving its energy
• paramedics to calm down- lowers heartbeat etc.

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The Nervous System
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The Nervous System
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The Peripheral Nervous System

• Links CNS to bodys sense receptors
• For each of the following, identify it as a
  function of the Somatic or Autonomic Nervous
  System.
• Sneezing
• Turning the page
• Scratching your head
• Breathing
• Kissing your date
• Digesting your food

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Communication in the Nervous System

• Nerves
• neural cables containing millions of axons
• part of the PNS (carry PNS info)
• connect the CNS with muscles, glands, and sense
  organs
• Extend through the body

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Communication in the Nervous System

• 3 neurons that carry info in the nervous system
• Sensory Neurons (afferent millions!)
• neurons that carry incoming information from the
  sense receptors to the central nervous system
• Motor Neurons (efferent millions)
• carry outgoing information from the CNS to
  muscles and glands
• Interneurons (billions!)
• CNS neurons that internally communicate / process
  sensory and motor neurons (most complex)

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The Central Nervous System

• The motherboard of our humanity
• 10s of billions of neurons
• Brain and spinal cord
• Spinal cord Information highway connecting PNS
  to the brain

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Reflexes

• Spinal Reflex Autonomic response to stimuli
  (Single sensory neuron, single motor neuron,
  interneuron..Brains not involved!)

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Pain Reflex

• Sensory neuron, interneuron, motor neuron
• a simple, automatic, inborn response to a sensory
  stimulus

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The Brain

• Center for all sensory information and voluntary
  movement (receives, interprets, decides)
• Without the brainno pain or pleasure, no
  voluntary movement

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Neural NetworksA Complex Mystery

• Neural Networks
• interconnected neural cells
• with experience, networks can learn, as feedback
  strengthens or inhibits connections that produce
  certain results
• computer simulations of neural networks show
  analogous learning

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In other words

• Neurons that fire together... wire together.

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The Endocrine System

• The bodys 2nd communication system
• Interconnected with nervous system

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Endocrine System

• ES glands produce hormones
• Hormones travel through bloodstream to affect
  body
• Influences growth, mood, metabolism, reproduction
  etc.
• Thus ES works to keep body in balance in response
  to stress, exertion, thoughts etc.
• Snail mail- Much slower to process, several
  seconds, but lasts longer

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Important Glands

• Pituitary Gland (the master gland..)
• Pea sized, in middle of brain
• Influences growth
• Influences other Endocrine glands release of
  hormones
• Controlled by hypothalamus (brain)
• Brain pituitary other glands hormones
  brain (complex system blend of Endocrine system
  and nervous systems)

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Pituitary Gland
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Adrenal Glands

• Located on top of kidneys
• Release epinephrine and norepinephrine
  (adrenaline and noradrenaline)
• Heart rate, blood sugar, blood pressure etc.

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Adrenal Glands
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What do you know about the human brain?

• Answer the following as true or false.
• The larger the brain, the smarter the animal.
• The brains structure is a better indicator of
  intelligence than its size.
• The right side of the brain controls the right
  side of the body, and so on with the left.
• You fall in love with your heart, not your brain.
• Your brain uses 20 of your bodys energy, but
  makes up only 2 of your bodys weight.

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What do you know about the human brain?

• True-False continued
• Your brain is about the size of a cantaloupe and
  is wrinkled like a walnut.
• Your brain feels like a ripe avocado and looks
  pink because of the blood running through it.
• The babys brain grows 3x in size during its
  first year.
• At birth, the human brain weighs 4/5 of a pound,
  while an adults weighs about 3 pounds.
• Your brain generates about 25 watts of power
  while awake- or enough to illuminate a light
  bulb.

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The typical human brain

• contains about 100 billion neurons
• consumes about ¼ of the bodys oxygen
• spends most of the bodies calories
• Is 70 water!!!
• weighs about 3 pounds

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The Brain

• Lesion
• tissue destruction
• a naturally or experimentally caused destruction
  of brain tissue

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Neuroimaging Techniques

• Mapping the brain

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Electroencephalogram (EEG) Detects Brain Waves

• Scans / measures electrical activity across brain
  
• can specify waves to specific stimulus
• Sleep research

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• CAT (computed tomography) Scan
• Multiple x-ray pictures 3D image of brain
  structure
• Structure only- not function
• Tumors, physical abnormalities

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• PET (positron emission tomography) Scan
• Can measure amount and movement of chemicals in
  the brain (glucose)
• Check brains activity to specific tasks (the
  more used, the more activity)
• Neurotransmitters and drugs

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• MRI (magnetic resonance imaging)
• Like CAT, but used magnetic fields to measure
  density and location of brain material
• soft tissue allows us to see structures within
  the brain

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MRI Scan
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• FMRI (Functional MRI) Reveals brains
  functioning as well as its structure (IOW MRI
  PET)
• Watches brain light up by concentrations of
  blood flow to specific areas

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The Old Brain (hind brain)Parts shared with
Distant Ancestors

• Life Support System

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• Brainstem
• the oldest part and central core of the brain,
  beginning where the spinal cord swells as it
  enters the skull
• responsible for automatic survival functions

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• Medulla muh-DUL-uh
• base of the brainstem
• controls heartbeat, blood pressure and breathing

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• Pons Help coordinate movement, facial
  expressions
• Connects hindbrain with mid forebrain

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Cerebellum

• Cerebellum sehr-uh-BELL-um
• the little brain attached to the rear of the
  brainstem
• coordinate voluntary movement and balance (fine
  muscle movements)

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Cerebellum
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Reticular Formation (Midbrain)

• Reticular Formation
• a nerve network in the brainstem that plays an
  important role in controlling arousal and sleep!

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Explain the significance of the next slide
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(No Transcript)
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The Brain
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• The Forebrain (Thought and Reason)
• Thalamus THAL-uh-muss
• the brains sensory switchboard, located on top
  of the brainstem (all but smell)
• it directs messages to the sensory receiving
  areas in the cortex and transmits replies to the
  cerebellum and medulla

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The Limbic System

• Limbic System
• a doughnut-shaped system of neural structures
• at border of the brainstem and cerebral
  hemispheres
• associated with emotions fear and aggression,
  drives such as hunger and sex
• includes the hippocampus, amygdala, and
  hypothalamus.

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The Limbic System
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The Limbic System
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• Amygdala ah-MIG-dah-la
• two almond-shaped neural clusters that are
  components of the limbic system and are linked to
  emotion (fear and aggression)

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Hippocampus

• Memory (more to come later)

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• Hypothalamus
• neural structure / below (hypo) the thalamus
  Basic Drives
• hunger
• thirst
• body temperature
• Sex drive (libido)
• helps govern the endocrine system via the
  pituitary gland
• is linked to emotion

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The Limbic System

• Electrode implanted in reward center

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Hemispheres of the Brain

• Left
• Language and logic
• Right
• Spatial, creative

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Why do most strokes affect the right side of the
body?

• Most strokes occur in the left hemisphere

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The Cerebral Cortex(Thin layer of densely packed
neurons .0039-inch)

• Cerebral Cortex
• intricate fabric of interconnected neural cells
  that covers the cerebral hemispheres (20 billion
  nerve cells!)
• bodys ultimate control and information
  processing center
• The larger the cortex, more adaptability,
  capacity for learning
• Wrinkles fissures (3 sq ft w/o them!)
• Perceiving, thinking, speaking
• Glial Cells
• cells in the nervous system that support,
  nourish, and protect neurons
• Aka neuron nannies or glue cells

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The Cerebral Cortex(Each hemisphere has 4 lobes)

• Frontal Lobes
• involved in speaking and muscle movements
  judgement, logic (abstract thought, emotional
  control)
• Parietal Lobes
• include the sensory cortex (sensory center/
  senses)
• Occipital Lobes
• Vision receive visual information from the
  opposite visual field
• Temporal Lobes
• Hearing, or auditory areas

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The Cerebral Cortex
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The Cerebral Cortex

• Motor Cortex
• at the rear of the frontal lobes / controls
  voluntary movements
• What parts of body occupy most cortical space?
• Fingers and mouth (require most precise control)
• Sensory Cortex
• at the front of the parietal lobes / registers
  and processes body sensations
• The more sensitive the body region, the more area
  occupied in the sensory cortex

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The Cerebral Cortex
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The Cerebral Cortex

• Functional MRI scan shows the visual cortex
  activated as the subject looks at faces

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Visual and Auditory Cortex
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Association Areas

• More intelligent animals have increased
  uncommitted or association areas of the cortex
• Association areas 75 of cortex
• Interprets, integrates and acts on info processed
  by sensory areas
• Associates sensory input with stored memories
  (complex mystery)

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Language and the Brain

• Brocas Area
• Location lower left frontal lobe / Role directs
  muscle movements making speech
• Wernickes Area
• Location left temporal lobe / Role language
  comprehension and expression
• Aphasia (language impairment)
• usually caused by left hemisphere damage either
  to Brocas area (impairing speaking) or to
  Wernickes area (impairing understanding)

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Specialization and Integration
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Specialization and Integration

• Brain activity when hearing, seeing, and speaking
  words

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Brain Reorganization

• Plasticity
• brains capacity to modify itself
• brain reorganizes / compensates after damage,
  injury
• children have the most plasticity
• Example blind and braille- one finger used
  sense of touch invades visual cortex

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Review Question

• When stroking the face of someone whos hand has
  been amputated, why did the subject feel the
  sensation not only on his face, but also on his
  amputated (phantom) fingers?
• Answer Hand area of the sensory cortex is no
  longer used, thus fibers from other sensory areas
  invade the space. (Note that the hand area is
  between the face and arm regions of the sensory
  cortex.)
• In other words. Plasticity!

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Plasticity
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Our Divided Brain

• True or False
• 1. Each hemisphere shares equally in performing
  all functions of the body.
• 2. The two hemispheres can be isolated by
  severing the corpus callosum.
• 3. Each hemisphere of the brain has a mind of
  its own.

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Our Divided Brain

• Corpus Callosum
• large band of neural fibers 200,000,000!
• connects the two brain hemispheres
• carries messages between the hemispheres (billion
  pieces of info / second!)

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Our Divided Brain

• The information highway from the eye to the brain

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Split Brain

• Isolate the 2 hemispheres by cutting the
  connecting fibers between them (corpus callosum)
  
• To remedy uncontrollable epileptic seizures
• Testing the split brain proves specific
  functions of each hemisphere

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The Split Brain ExperimentDr. Gazzaniga-
1967Stare at the Dot..

• he.art
• Which word would the split-brain patient
  verbalize seeing? Why?
• Which word, when asked to point with his left
  hand, would he report seeing? Why?

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Split BrainExplain the following
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The Split brain

• 1. If this visual was shown to the right
  hemisphere of a split brain patient, how might
  the patient identify the object?

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The Split Brain

• Interesting facts about the split brain
• Subjects can simultaneously draw different
  figures with the left and right hand.
• When the 2 hemispheres are at odds, the left will
  rationalize reactions it doesnt understand.
• The hemispheres are an odd couple, each with a
  mind of its own.

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The Split BrainWhich hemisphere is more active
with

• Right brain
• Right brain
• Left brain
• Right brain
• Right brain
• Right brain

• Simple requests
• Perceiving objects
• Decision making (deliberative)
• Quick intuitive responses
• Recognizing faces
• Perceiving , expressing emotion

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Hemispheric Differences in the Intact Brain

• Hemispheric specialization lateralization
• Blood flow, glucose, brain waves detected between
  hemispheres for perceptual tasks and speaking,
  calculating tasks (EEG, PET, FMRI)
• Sedative to artery to specific hemisphere alters
  specific functions of the body
• If left hemisphere is sedated, what functions
  would be lost?
• Language, right side of body limp
• If sedative to right hemisphere?
• Difficulty identifying themselves in altered
  photo, left side limp

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Questions to consider.

• 1. If a word is flashed to your right hemisphere
  (through your left visual field), why does it
  take you slightly longer to state what you see
  than it would if flashed to your left hemisphere?
• Process time through the corpus callosum
• Which hemisphere would a deaf person use for sign
  language?
• right (visual / spatial) or left (language)?
• Left to the brain, language is language

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Handedness

• What percentage of humans are right handed?
• 90
• What ultimately makes you right or left handed?
• Genetics? Pre-natal? Social-Cultural?
• What expressions can you think of that
  discriminate against lefties?
• Right on / right hand man / righteous / right
  mind -- out in left field / left-handed
  compliment

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Lefties tend to be..

• Musicians
• Mathematicians
• Professional baseball / cricket players
• Architects
• artists

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Disappearing Southpaws

• The percentage of left-handers decreases sharply
  in samples of older people (adapted from Coren,
  1993).

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Brain Structures and their Functions