Neuroscience

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Neuroscience

• Chapter Two

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Neurons

• Cells that receive and transmit information
• A nerve cell that communicates in electrical and
  chemical form
• glial cells-support cells nutrition insulation

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Neurons-3 main parts

• Cell body
• Dendrites
• Axons
• Cell body has the genetic material that is found
  in virtually all cells of the body

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2. Dendrites

• Branching out from the cell body are fibers
  called dendrites
• Receive messages from other neurons
• Dendrites with more branches get more info

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Pruning

• Underused neurons are inactivated
• If experience does not activate that part of
  brain, dendrites not established
• Message USE IT or LOSE IT

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3.Axons

• Single elongated tube that extends from cell body
• Transmits information
• Neurons have one, or none

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Myelin Sheath

• Axons of most neurons covered by this
• White, fatty covering
• Not continuous coating, it has gaps called the
  Nodes of Ranvier

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Growth in myelin sheath

• Also known as myelination
• Most growth between 18 months and 4 years
• Sheath that surrounds neurons increases speed of
  neural messages

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Myelination

• Myelinated neurons go faster
• Range from 2 mph to 270 mph

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Damage to Myelin Sheath

• Multiple sclerosis
• Most common in No. Colorado and along the 37th
  parallel
• 75 of victims women

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Action Potential

• communication

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Stimulus Threshold

• a certain minimum of stimulation from other
  neurons activates s.t.
• All-or-none law once stimulated, an action
  potential occurs (no half-way, no partial)

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Basic organization of the Brain
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Fetal Brain

• Begins w/ a neural tube that forms about 2 weeks
  after conception
• Drinking alcohol (ETOH) at this point can be
  especially damaging

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Fetal Alcohol Syndrome

• Leading cause of preventable mental retardation
• Facial deformities no philtum, small, widely
  spaced eyes
• Lifelong problems hyperactivity, impulsivity

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Brain Growth

• At birth, 25 of adult weight
• By 4 years old, 80 of adult weight

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Neurogenesis

• Development of new neurons
• Thought until late 1990s that we only lost them
• Actually generated throughout life

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Hindbrain

• Hindbrain-at base of brain and connects brain to
  spinal cord
• Medulla-contains centers that control autonomic
  functions
• Cerebellum-balance, coordinated muscle movements

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Midbrain

• Segment of brain stem between hindbrain
  forebrain
• Relay station for auditory visual information

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Forebrain

• 90 of the brain
• Cerebrum complex thought
• Cerebral cortex- convoluted outer layer --2
  hemispheres
• Each hemisphere has 4 lobes
• Also contains limbic system (emotion)

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Corpus callosum

• The structure that connects the 2 cerebral
  hemispheres
• Thick band of fibers

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4 Lobes

• Each hemisphere has 4 lobes
• Temporal lobe-primary auditory cortex
• Occipital lobe-primary visual cortex
• Parietal lobe-sensory information

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4th lobe

• Frontal lobe
• Planning, initiating, executing voluntary
  movements
• Judgment
• Also on frontal lobe primary motor cortex

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Plasticity of the Brain

• Use of an area enlarges that area of the brain
• Damage may be overcome in some cases

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Lateralization

• Specialized hemispheres

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Pierre Paul Broca

• Damage to a certain area causes consistent loss
• No production of speech

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Karl Wernicke

• Damage to another area in left hemisphere
  (temporal lobe)
• Couldnt understand spoken or written speech

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Lateralization

• Specialization of functions in each side of the
  cortex (hemispheres).
• Previously thought that it mattered if you were
  left or right handed for language functioning

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Brain Differences

• Brains of left/right handed people are different.
• Finding male/female differences, too.
• maybe sexual orientation differences.

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Lefties more prone to

• Have learning disabilities
• Autism, dyslexia, stuttering
• 6 x more likely to be in an accident
• 4x more likely to die while driving

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Lefties over represented

• In populations of mentally retarded (3x normal
  rate)
• Also in populations of gifted
• Famous writers, thinkers lefties Da Vinci,
  Einstein, Napoleon, Mark Twain

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Speech Grammar

• 97 of right handed people have a speech center
  in left hemisphere
• 68 of lefties do, too
• If LH and pen faces bottom of page, likely to be
  L hemisphere for language.