Your Brain

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Your Brain!

• Major Structures The Cerebrum

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LE 48-19
Central nervous system (CNS)
Peripheral nervous system (PNS)
Brain
Cranial nerves
Spinal cord
Ganglia outside CNS
Spinal nerves
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• The brain provides the integrative power that
  underlies the complex behavior of vertebrates
• The spinal cord integrates simple responses to
  certain kinds of stimuli (reflexes) and conveys
  information to and from the brain

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CNS

• Axons within the CNS are often found in bundles
  that have a whitish appearance
• white matter
• - composed of myelinated axons
• - carries information between the nerve cells
  in the brain and spinal cord
• gray matter
• - consists of unmyelinated axons - the
  thinking brain

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LE 48-20
Grey matter
White matter
Ventricles
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The cerebrum
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The cerebrum

• The cerebrum has right and left hemispheres
• Each hemisphere consists of a cerebral cortex
  (grey matter) overlying white matter and basal
  nuclei
• A nucleus is a CNS structure that is composed
  mainly of grey matter, and is a hub for
  electrical signals in a neural subsystem
• lateral geniculate nucleus is involved in the
  visual system
• raphe nuclei are involved in sleep
• All the axons ending at a specific nucleus tend
  to use the same neurotransmitter at their
  synapses
• A thick band of axons called the corpus callosum
  provides communication between the hemispheres

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The cerebrum

• Functions
• - Language and communication
• - Speech and language
• - Movement
• - The cerebrum is responsible for voluntary
  motor function - When this part of the brain is
  damaged, it is unable to send signals to motor
  neurons on muscles and there is a loss of
  muscular power
• - Olfaction (sense of smell)
• - Memory
• - Memory formation is associated with the
  hippocampus
• - A patient had both his hippocampuses (left
  and right) surgically removed to treat severe
  epilepsy
• - anterograde amnesia, or the inability to form
  new memories
• - This was the case in the film Memento

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LE 48-26
Right cerebral hemisphere
Left cerebral hemisphere
Corpus callosum
Neocortex
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Left vs. Right

• Information stored on one side of the brain is
  not always present on the other
• R side ? visual patterns and spatial awareness
• L side ? verbal skills
• Each hemisphere controls the movement of the
  opposite side

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Left vs. Right

• Left brain functions linear processing,
  concrete-oriented, math quantity - perception of
  counting/measurement, present and past, language
  grammar/words, pattern
• Right brain functions simultaneous processing,
  abstract-oriented, math quality-perception of
  shapes/motions, present and future, language
  intonation/emphasis, spatial perception

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Cortical homunculus

• A cortical homunculus (little man) is a
  physical representation of the sensorimotor
  cortex
• The portion of the human
• brain responsible for the
• movement and exchange
• of sense and motor
• information

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Human homonculus