1. Functional organization of the primary motor cortex Premotor cortex
Corticospinal and corticobulbar pathways: upper motor neurons that initiate complex voluntary movements
Functional organization of the primary motor cortex
Premotor cortex
Damage to descending motor pathways
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3. Upper motor neurons in cerebral cortex (primary motor cortex)
Corticospinal and corticobulbar pathways: upper motor neurons that initiate complex voluntary movements
Upper motor neurons in cerebral cortex (primary motor cortex)
In adjacent and interconnected areas of the frontal lobe
Together mediate planning & initiation of complex temporal sequences of voluntary movements.
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5. Corticospinal and corticobulbar pathways
Primary motor cortex receives regulatory input:
From basal ganglia and cerebellum
-> relays in ventrolateral thalamus
From sensory regions of the parietal lobe
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6. Primary motor cortex
Low threshold for eliciting movements through electrical stimulation
Descending pathways to lower motor neurons in the brainstem and spinal cord.
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8. Organization of the primary motor cortex
Upper motor neurons are pyramidal cells in layer V.
Their axons descend to the brainstem and to spinal motor center in the corticobulbar and corticospinal tracts.
--> then run to the base of the pons
--> to medulla through medullary pyramids….
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10. Lateral corticospinal tract
Direct pathway from the cortex to the spinal cord (lateral portions of the ventral horn and intermediate gray matter)
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12. Indirect pathway
from motor cortex to 2 sources of upper motor neurons in the brainstem (red nucleus and reticular formation)
Motor cortex--> reticular formation --> medial region of the spinal cord.
Motor cortex--> red nucleus--> lateral region of the spinal cord.
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13. Functional organization of the primary motor cortex
When stimulated, muscles on the opposite side of the body contract.
Has complete representation of body’s musculature.
Greater space for fine motor control than for less precise motor control
Very focal stimulation --> organized movement (excitation and inhibition)
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14. Motor Cortex Overlap of regions that initiate different movements.
A particular movement can be elicited by widely separated sites.
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15. Motor cortex Recorded neural activity during voluntary movement.
Motor cortex neurons direct recruitment of lower motor neurons
Force
Direction
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16. Motor cortex
Upper motor neurons encode a movement rather than individual muscles.
A movement can involve several different lower motor neuron pools
Each arm movement is encoded by concurrent discharges of a large population of neurons
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17. Premotor cortex -movement selection
Reciprocal connections
with the primary motor cortex
And project axons through corticobulbar and corticospinal pathways
Uses information from other cortical regions
Active during association of visual (sensory) to movement.
Wed. Jan. 24, 2006