The Nervous System Pathways and Functions
Transcript of The Nervous System Pathways and Functions
C h a p t e r
16
The Nervous System —
Pathways and Higher-Order
FunctionsPowerPoint® Lecture Slides
prepared by Jason LaPres
North Harris College
Houston, Texas
Copyright © 2009 Pearson Education, Inc.,
publishing as Pearson Benjamin Cummings
Introduction
There is a continuous flow of information between
the brain, spinal cord, and peripheral nerves.
Many subtle forms of interaction, feedback, and
regulation link higher centers with the
various components of the brain stem.
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Sensory and Motor Pathways
Nerve pathways, called tracts, connect the CNS and PNS
Ascending (sensory) pathways
Descending (motor) pathways
Tract name often indicates its origin and destination
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Sensory and Motor Pathways
Sensory pathways
The posterior column pathway
The spinothalamic pathway
The spinocerebellar pathway
Sensory pathways usually contain three neurons:
First-order neuron — to the CNS
Second-order neuron — an interneuron located in either the
spinal cord or the brain stem
Third-order neuron — carries information from the
thalamus to the cerebral cortex
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Sensory and Motor Pathways
Figure 16.1 Ascending (Sensory) Pathways and Tracts in the Spinal Cord
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Sensory and Motor Pathways
Figure 16.2a The Posterior Column, Spinothalamic, and Spinocerebellar Sensory Pathways (Posterior Column Pathway)
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Sensory and Motor Pathways
Figure 16.2b The Posterior Column, Spinothalamic, and Spinocerebellar Sensory Pathways (Anterior Spinothalamic Tract)
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Sensory and Motor Pathways
Figure 16.2c The Posterior Column, Spinothalamic, and Spinocerebellar Sensory Pathways (Lateral Spinothalamic Tract)
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Sensory and Motor Pathways
Figure 16.2d The Posterior Column, Spinothalamic, and Spinocerebellar Sensory Pathways (Spinocerebellar Pathway)
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Sensory and Motor Pathways
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Sensory and Motor Pathways
Motor pathways
The corticospinal pathway
The corticobulbar tracts
The corticospinal tracts
The medial and lateral pathways
Motor pathways usually contain two neurons
Somatic nervous system (SNS)
Upper motor neuron — within CNS
Lower motor neuron — from CNS to effector
Autonomic nervous system (ANS)
Preganglionic neuron
Ganglionic neuron
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Sensory and Motor Pathways
Figure 16.3a Motor Pathways in the CNS and PNS (Somatic Nervous System)
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Sensory and Motor Pathways
Figure 16.3b Motor Pathways in the CNS and PNS (Autonomic Nervous System)
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Sensory and Motor Pathways
Figure 16.4a The Corticospinal Pathway and Descending Motor Tracts in the Spinal Cord (Corticospinal Pathway)
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Sensory and Motor Pathways
Figure 16.4b The Corticospinal Pathway and Descending Motor Tracts in the Spinal Cord (Cross-Sectional View of Descending Motor Tracts in the Spinal Cord)
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Sensory and Motor Pathways
Figure 16.5 Nuclei of the Medial and Lateral Pathways
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Sensory and Motor Pathways
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Sensory and Motor Pathways
Figure 16.6 Somatic Motor Control
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Higher-Order Functions
Higher-order functions have the following
characteristics:
They are performed by the cerebral cortex.
They involve complex interconnections and
communication between areas within the cerebral cortex
and between the cerebral cortex and other areas of the
brain.
They involve both conscious and unconscious information
processing.
They are not part of the programmed “wiring” of the brain;
therefore, the functions are subject to modification and
adjustment over time. A.K.A — learning
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Higher-Order Functions
Figure 16.7a Functional Areas of the Cerebral Cortex (Motor and Sensory Areas of the Cerebral Cortex)
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Higher-Order Functions
Integrative Regions of the Cerebral Cortex
Cortical areas that act as centers for complex
sensory stimuli and motor responses
General interpretive area
Receives information from all sensory association areas
Only present in one hemisphere, usually the left
Speech center
Regulates patterns of breathing and vocalization
Prefrontal cortex
Coordinates information from the secondary and special
association areas of the cortex
Performs abstract intellectual functions
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Higher-Order Functions
Figure 16.7b Functional Areas of the Cerebral Cortex (Higher-Order Integrative Regions of the Cerebral Cortex)
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Higher-Order Functions
Figure 16.7c Functional Areas of the Cerebral Cortex (Selected Brodmann’s Areas of the Cerebral Cortex)
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Higher-Order Functions
Figure 16.8 Hemispheric Specialization
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Higher-Order Functions
Memory
Process of accessing stored bits of information acquired through experience
Short-term memories last seconds to hours
Long-term memories can last for years and are stored in the cerebral cortex
Memory consolidation— conversion from a short-term memory to a long-term memory
The amygdaloid body and the hippocampus (limbic system) are essential to memory consolidation
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Higher-Order Functions
Figure 16.9 The Reticular Activating System
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Higher-Order Functions
TABLE 16.3 States of Awareness
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Aging and the Nervous System
Common, age-related anatomical changes
in the nervous system include the following:
A reduction in brain size and weight
A reduction in the number of neurons
A decrease in blood flow to the brain
Changes in synaptic organization of the brain
Intracellular and extracellular changes in CNS
neurons
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