05b motor system upper motor neuron
Transcript of 05b motor system upper motor neuron
Voluntary Motor Control
Motor Cortex
Functional Organization of the Primary Motor Cortex
The major inputs to the motor cortex in monkeys
Corticospinal Tract
Convergence of Motor Control on the Anterior Motor Neuron
Experimental apparatus developed to record the activity of single neurons in awake primates trained to perform specific movements : Ed Evarts 1960
Direct corticospinal control of motor neurons is necessary for fine control of the digits
Activity in Individual Neurons of the Primary Motor Cortex Is Related to Muscle Force and Direction of Movement
Spike Triggered Averaging 1970
Motor Cortical Cell Firing with Force Generated
Directional tuning of an upper motor neuron in the primary motor cortex
Corticomotoneuronal (CM) cell is active depends on the motor task
Different areas of cortex are activated during simple, complex, and imagined sequences of finger movements (Xenon PET)
Cell activity in the motor cortex depends on whether a sequence of movements is guided by visual cues or by prior training
A set-related neuron in the dorsal premotor area becomes active while the monkey prepares to make a movement to the left
The visuomotor transformations required for reaching and grasping involve two different pathways
Individual neurons in the ventral premotor area fire during specific hand actions only
An individual cell in the ventral premotor area is active whether the monkey performs a task or observes someone else perform the task
The Somatotopic Organization of the Motor Cortex Is Plastic
As a movement becomes more practiced, it is represented more extensively in primary motor cortex
Summary
Primary Motor Cortex:– Codes force and direction of movement– Spinal motor neuron are directly under control for precise
movement.Dorsal Premotor Cortex
– Movement related neuron encodes sensorimotortransformation for visual and sensory cue
– Fire before movementVentral Premotor Cortex
– Encodes learned motor act fire before movement
All cortical neurons are adaptable and plastic
Modulation of Movement by the Basal Ganglia
Motor components of the human basal ganglia
Anatomical Organization of Basal Ganglia Input
Output of Basal Ganglia
The somatotopic organization of the basal ganglia-thalamocortical motor circuit
Disinhibition
Organization of Cerebellum
Functional organization of cerebellum
Input of Cerebellum
Cerebellar Output
Vestibulocerebellum
Neocerebellum
The spinocerebellum contains two somatotopic neural maps of the body
Cerebellar Pathway