Post on 21-Dec-2015
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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 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