Introduction to the nervous System

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Introduction to the nervous System
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Divisions of the nervous system

• Central nervous system - encased in bone
• Spinal cord
• brain
• Peripheral nervous system everything else
• Somatic nervous system voluntary control
• Sensory nerves
• Motor nerves
• Autonomic nervous system no conscious control
• Sympathetic nervous system fight or flight
  response
• Parasympathetic nervous system -

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The spinal cord
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Function of the spinal cord

• White matter nerve fibers running to and from
  the brain
• Gray matter neurons and synapses, mediates
  reflexes
• Dorsa horn sensory
• Ventral horn - motor

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The Brain
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Hindbrain

• Medulla involved with autonomic system
  regulating breathing and vomiting, etc.
• Reticular activating and raphe system
  activates the brain maintaining arousal or
  reduces arousal for sleep
• Locus coeruleus mood control and alerting
  response
• Cerebellum coordination of voluntary movements,
  eye saccades, and simple learning

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Basal ganglia

• Important for the control of voluntary movement
• Memory for spatial location
• Provides feedback to cortex about movement and
  initiation of movement

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Periaqueductal Gray

• Carries information about pain from spinal cord
  to the cortex
• Punishment center8

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Limbic System

• Hypothalamus
• Controls eating drinking, sexual, etc. behaviors
• Hippocampus
• Formation of new memories
• Septum
• Emotion and emotional memories
• Amygdala
• Implements aggressive behavior
• Active in fear conditioning

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Cortex

• Posterior and central areas primarily concerned
  with sensory and motor functions
• Frontal lobe inhibition of behaviors,
  expression of emotion, availability of rewards
• Prefrontal areas
• Orbitofrontal learning reward associations
• Prefrontal working memory and thinking
• Dorsolateral maintenance of attentional demands
  of a task
• Anterior cingulate mediates attention,
  inhibition of dominant behaviors

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Development of the Nervous System

• Formation of neurons neurogenesis- largely
  prenatal
• Majority of cells develop in first 3 months
  gestation - up to 150,000 cells per minute easily
  disrupted by chemicals and radiation
• Migration pre and post natal
• Cells move from where they were formed to their
  target area
• They move either toward or away from chemicals
  released by areas of the brain
• Interconnections develop largely postnatal
• Programmed cell death

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Methods of investigating drug effects on the
nervous system

• Electroencephalograms (EEG) Electrodes are
  attached to the subjects scalp, and the device
  records the patterns of brain waves.
• Event-Related Potentials The momentary changes
  in electrical activity of the brain when a
  particular stimulus is presented to the subject.

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Methods of investigating drug effects on the
nervous system (cont.)

• Imaging Technology
• Magnetic Resonance Imaging (MRI) Gives clear
  pictures of the structure of the brain.
• Functional MRI Image shows regions of the brain
  with heightened neural activity, with different
  colors reflecting high or low levels of blood
  flow, oxygen uptake, and the like.
• PET scans- use radioactive labels attached to
  glucose