Transcript Introduction to the nervous sytem

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 subject’s
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
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