| Date post: | 19-Dec-2015 |
| Category: |
Documents |
| View: | 216 times |
| Download: | 0 times |
Copyright © 2006 by Allyn and Bacon
Chapter 8The Sensorimotor System
How You Do What You DoThis multimedia product and its contents are protected under copyright law. The following are prohibited by law:• any public performance or display, including transmission of any image over a network;• preparation of any derivative work, including the extraction, in whole or in part, of any images; • any rental, lease, or lending of the program.
Copyright © 2006 by Allyn and Bacon
3 Principles of Sensorimotor Function Hierarchical organization
Association cortex at the highest level, muscles at the lowest
Parallel structure – signals flow between levels over multiple paths
Motor output guided by sensory input Learning (experience) changes the nature
and locus of sensorimotor controlConscious to automatic, for example
Copyright © 2006 by Allyn and Bacon
Copyright © 2006 by Allyn and Bacon
2 Major Areas of Sensorimotor Association Cortex Each composed of several different
areas with different functions Some disagreement exists about how
to divide the areas up Posterior parietal association cortex Dorsolateral prefrontal association
cortex
Copyright © 2006 by Allyn and Bacon
Posterior Parietal Association Cortex
Integrates information aboutBody part locationExternal objects
Receives visual, auditory, and somatosensory information
Outputs to motor cortex
Copyright © 2006 by Allyn and Bacon
What affect does damage to the posterior parietal area have? Apraxia – disorder of voluntary
movement – problem only evident when instructed to perform an action – usually a consequence of damage to the area on the left
Contralateral neglect – unable to respond to stimuli contralateral to the side of the lesion - usually seen with large lesions on the right
Copyright © 2006 by Allyn and Bacon
Dorsolateral Prefrontal Association Cortex Input from posterior parietal cortex Output to secondary motor cortex,
primary motor cortex, and frontal eye field
Evaluates external stimuli and initiates voluntary reactions – supported by neuronal responses
Copyright © 2006 by Allyn and Bacon
Copyright © 2006 by Allyn and Bacon
Secondary Motor Cortex
Input mainly from association cortex Output mainly to primary motor cortex At least 7 different areas
2 supplementary motor areas SMA and preSMA
2 premotor areas dorsal and ventral
3 cingulate motor areas
Copyright © 2006 by Allyn and Bacon
Motor homunculus
Copyright © 2006 by Allyn and Bacon
The Motor Homunculus
Control of hands involves a network of widely distributed neurons
Stereognosis – recognizing by touch – requires interplay of sensory and motor systems
Some neurons are direction specific – firing maximally when movement is made in one direction
Copyright © 2006 by Allyn and Bacon
Cerebellum and Basal Ganglia
Interact with different levels of the sensorimotor hierarchy
Coordinate and modulate May permit maintenance of visually
guided responses despite cortical damage
Copyright © 2006 by Allyn and Bacon
Basal Ganglia
A collection of nuclei Part of neural loops that receive
cortical input and send output back via the thalamus
Modulate motor output and cognitive functions
Copyright © 2006 by Allyn and Bacon
4 Descending Motor Pathways
2 dorsolateralCorticospinal Corticorubrospinal
2 ventromedialCorticospinalCortico-brainstem-spinal tract
Both corticospinal tracts are direct
Copyright © 2006 by Allyn and Bacon
Copyright © 2006 by Allyn and Bacon
