Neuroscience

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Neuroscience Behavior

• Chapter 2

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Introduction

• We are BIO-PSYCHO-SOCIAL systems
• Biological Psychologists
• study connections between biological activity and
  psychological events
• Look at sleep, depression, stress, etc.
• Everything that is psychological is biological
• Every thought, feeling is a biological happening
• Phrenology
• bumps on skull could reveal mental abilities,
  traits
• Idea Specific brain regions have particular
  functions

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Neural Communication

• Neurons
• nerve cells that consists of
• Cell body
• Fibers
• Dendrite receive information (short)
• Axon Fibers (some very long)
• Pass info to other neurons, muscles, glands
  (Away)
• Sometimes very long, several feet in body
• Myelin sheath (MY-uh-lin)
• Insulation for axons of some neurons
• Helps to speed impulses
• Multiple sclerosis degeneration of myelin sheath

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Action Potential

• Action Potential
• impulse fired off by neuron
• when it receives signals
• from sense receptors (pressure, heat, light)
• from chemicals from other neurons
• brief electrical charge that travels down axon
• Generated by movement of positively charged atoms
  in and out of channels in axons membrane
• travels 2-200 mph

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Ions

• Neurons generate electricity from chemical events
• This process involves exchange of Ions
• Ions electrically charged atoms
• Resting Potential
• Fluid interior of resting axon has excess of
  negatively charged ions
• Fluid exterior has more positively charged ions.
• Selectively permeable
• Axons service is selective about what it allows
  inside
• Ex Resting axon has gates that block certain
  ions

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When Neuron Fires

• First part of axon opens its gates
• Positively charged sodium ions flood through the
  membrane channel
• This depolarizes that part of the axon
• Like dominos falling, the axons channels
  beginning opening

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Refractory Period

• Resting pause
• Neuron pumps positively charged sodium atoms back
  outside.
• Then it can fire it again.
• In myelinated neurons, the action potential hops
  from one myelin sausage to the next

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Signals

• Neuron receives signals on its dendrites and cell
  body from other neurons
• Excitatory signals accelerator
• Inhibitory signals brake
• Threshold when excitatory signals minus
  inhibitory signals exceed a minimum intensity,
  the combined signals trigger an action potential.
• Action potential travels down the axon

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Intensity

• Neurons reaction is all-or-nothing
• Either it fires or it doesnt
• Strength of stimulus does not affect speed
• Strong stimulus can
• trigger more neurons to fire
• of neurons firing
• and to fire more often
• of firings in period of time

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How Neurons Communicate

• Synapse
• Junction between axon terminal of one neuron and
  receiving neuron
• Less then one millionth of inch wide
• Synaptic Gap/Cleft gap itself

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Crossing Synapse

• When action potential reaches axons end, it
  triggers release of chemical messengers
  (neurotransmitters)
• Neurotransmitters cross gap and bind to receptor
  sites on receiving neuron (key fits lock)
• opens channels on receiving site
• ions enter receiving neuron
• cause it to be excited or inhibited
• Reuptake excess neurotransmitters reabsorbed by
  sending neuron

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Role of Neurotransmitters

• Neurotransmitters affect behavior or attitudes
• (Page 62- Chart)
• Brain has natural opiate receivers therefore
  must have naturally occurring opiates
• Endorphins
• Neurotransmitters similar to morphine
• endogenous (produced within) morphine
• (morphine within)
• Linked to pain control to pleasure

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Affect of Drugs on Neurotransmittors

• Drugs (ie. heroin, morphine)
• stop natural production of natural opiates
• Agonists - excites
• Mimics neurotransmitters that excite
• Or blocks neurotransmitters reuptake
• Can create high by increasing arousal/pleasure
• Antagnoists inhibits
• May inhibit neurotransmitters release
• May occupy receptor site and block its effect

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Blood Brain Barrier

• Allows brain to fence out unwanted chemicals
  circulating in the blood
• Some chemicals dont have right shape to go
  through this barrier
• Ex dopamine vs. L-dopa

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Nervous System

• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)
• Nerves
• neural cables of axon bundles
• Connect central nervous system with muscles,
  glands, organs
• 3 Types of Neurons in Nervous System
• Sensory Neurons
• send info from sense receptors to brain and
  spinal cord
• from senses
• Interneurons
• majority of neurons internally communicate
  intervene between sensory inputs and motor
  outputs
• Motor neurons
• takes info from CNS to muscles/glands
• to motor

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Peripheral Nervous System

• PNS connects the CNS to rest of the body (sense
  receptors, muscles, glands)
• Sensory Motor Neurons
• Carry this information
• Nerves sensory/motor neurons bundled into
  electrical cables

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PNS

• Two components of PNS
• Somatic
• Controls movement of skeletal muscles (hand
  turning page)
• Autonomic
• Controls glands and muscles of internal organs
• Usually operates on own
• i.e. heartbeat, digestion
• Made up of Sympathetic Parasympathetic

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Sympathetic Nervous System

• Arouses us for defensive action
• Accelerate heartbeat
• Slow digestion
• Raise blood sugar
• Dilate arteries
• Cool with perspiration

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Parasympathetic

• Opposite effect of Sympathetic
• Calms the body
• Conserves energy
• Decreases heartbeat
• Lowers blood sugar, etc.

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CNS

• Made up of
• Spinal Cord
• Brain
• Spinal Cord
• Connects peripheral nervous system to brain (page
  66)
• Reflex - automatic response to stimuli

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The Nervous System

• 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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How We Know the Brain

• Observe effects of brain diseases and injuries
• Stimulate/lesion parts of brain
• Record brains electrical activity with
  Electroencephalogram (EEG)

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Other Methods

• Computed Tomography (CT) Scan
• Takes X-ray pictures of brain
• Also called CAT scan
• Positron Emission Tomography (PET)
• Shows brains digestion of radioactive glucose
• Magnetic Resonance Imaging (MRI)
• Signals from atoms become computer generated
  images
• Can show activity of brain by detecting blood
  flow
• Allows us to see structures within the brain

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Brain Structures

• Brainstem
• Oldest region
• Begins where spinal cord enters skull
• Responsible for automatic survival functions
• Made up of
• Medulla
• base of brainstem
• controls for heartbeat and breathing
• Reticular Formation network of neurons that
  helps to control arousal

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Thalamus

• Brains sensory switchboard (73)
• Joined pair of egg-shaped structures
• Receives info from senses except smell
• Routes this info to higher brain regions
• Coordinates electrical oscillations
• Slow during sleep
• Speed up to cause waking

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The Brain

• Cerebellum sehr-uh-BELL-um
• Two wrinkled hemispheres
• the little brain attached to the rear of the
  brainstem
• it helps coordinate voluntary movement and
  balance
• Helps with nonverbal learning and memory

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Limbic System

• Influences emotions motives
• Controls hormones
• Doughnut-shaped neural system
• Includes hippocampus, amygdala, hypothalamus
• Amygdala influences aggression/fear
• Hypothalamus
• influences hunger, thirst, body temp, sexual
  behavior
• reward centers

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Cerebral Cortex

• Thin wrinkled surface layer on cerebral
  hemispheres
• Sheet of cells 1/8th inch thick
• 20-23 billion nerve cells
• 9 X as many glial cells
• Guide neural connections
• Provide nutrients myelin
• Mop up ions and neurotransmitters
• Support, nourish, protect neurons
• Where information is processed and complex
  functions are performed
• Bodys ultimate control center

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Lobes

• Frontal
• behind forehead
• Planning area, involved in speaking muscle
  movements
• Parietal
• top and to rear
• Includes sensory cortex
• Occipital
• back of head (out)
• Receives visual information
• Temporal
• Above ears (temples two)
• Receives auditory information

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Functions of Cortex

• Motor
• Controls movement of different body parts on
  opposite side of body
• Sensory
• Receives incoming information from senses and
  movement
• Behind motor cortex
• More sensitive a body region, greater area on
  sensory cortex

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Cortex Associations Areas

• Association Areas-areas in cortex other than
  sensory, motor areas
• Neurons in association areas integrate
  information
• Associate sensory information with memories
• Interprets information sent by sensory areas
• Ex Association areas in frontal lobes help up
  to judge, plan, process new memories
• Ex Phineas Gage

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Cerebral Cortex Language

• Aphasia impaired use of language due to damage
  of brain area
• Can speak but cannot read
• Can read but cannot speak
• Brocas area (in left frontal lobe area)
• Language expression
• Controls muscle movement involved in speech
• Damage disrupts speaking
• Wernickes area (in left temporal lobe area)
• Controls language reception/comprehension
• Damage disrupts understanding of language

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Brain

• Plasticity
• Brain is able to modify itself
• Brain may reorganize itself in response to damage
• Corpus Callosum
• Connects two hemispheres
• Transmits information from one hemisphere to
  another
• Split Brain
• the two hemispheres of the brain are isolated by
  cutting the connecting fibers (mainly those of
  the corpus callosum) between them

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Endocrine System

• Glands secrete hormones
• Hormones chemical messengers, produced in one
  tissue and affect another
• Slower system than nervous system but effects may
  last longer
• Adrenal glands
• On top of kidneys
• Release epinephrine norepinephrine
• Pituitary Gland
• Base of brain
• Growth hormone
• Triggers sex glands to release sex hormones