Control of Movement. Patterns of Connections Made by Local Circuit Neurons in the Intermediate Zone of the Spinal Cord Gray Matter. Long distance interneurons project bilaterally, innervate multiple segments. Used for posture control.
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Long distance interneurons project bilaterally,
innervate multiple segments.
Used for posture control.
Short distance interneurons project over a few segments, remain ipsilateral.
Used for distal muscle groups.
EMG= elecromyography. Measure muscle APs
Gastrocnemius stimulation happens before biceps
cut reticulospinal tract Biceps will fire but not Gastrocnemius
Motor cortex makes two types of projections.
lateral corticospinal and
rubrospinal tracts, distal
fine motor movements.
Ventral corticospinal tract,
Architecture of motor cortex is different than the sensory cortex.
The corticospinal tract.
Monkey trained to move joystick in response to light
Yellow – activity of neuron is increased.
Purple – activity is decreased.
Neurons have “preferred direction”
Activity of a single neuron in motor cortex
anticipates future movement.
Individual neurons tuned too broadly to accurately predict movement
Populations of neurons can calculate a direction. Summed population responses give the actual direction of movement.
Motor cortex areas
Photograph of sagittal section through brain stem and cerebellum