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