Review on Voluntary Movement and Motor Cortex

What are the 3 main subdivisions of the motor cortex?

Primary motor cortex (M1), premotor area (PMA), supplementary motor cortex (SMA)

The primary motor cortex (M1) is ?

The locus in the cortex where microstimulation can cause movement with the lowest stimulation intensities

Describe the of the body map contained by the primary motor cortex

Distorted, not continuous, neurons that control movement of related body parts are not cleanly segregated, fine scale intermixing

Fine scale intermixing accounts for?

electrical stimulation of neurons at a single location in M1 can cause movement around multiple joints

Neurons in M1 represent the ________ around a single joint rather than __________

direction of force; direction of movement

What does it mean that an individual M1 neuron is broadly tuned?

It has a preferred direction where it fires at the highest rate, but will fire some extent over a broad range of directions

Accurate decoding of the direction of a ______ can require ______ neurons or less

simple movement; 100

M1 neurons project axons where?

Down through the pyramidal tract into the spinal cord grey matter where an axon can activate a motorneuron pool or diver to activate flexor/extensor neurons

Where do many premotor cortex neurons project?

primary motor cortex (M1)

How are PMA neurons different from M1 neurons?

firing is not directly tied to movement

continue to fire during a delay period while waiting for movement

only fire during preparation for a particular movement

How are PMA neurons diverse?

ramp up during delay period, ramp down, fire constantly, mixture of transient and tonic firing

PMA neurons can abstract away from ___?

specific muscles involved in producing a movement

PMA neurons can fire in relation to specific ____ _____ shapes put not a ______ grip

precision grip; power

How do PMA neurons act like mirrors?

fire either when one executes movement or when it sees a movement

When is the supplementary motor area activated?

execution of complex motor sequences

SMA neurons can be tuned to _____?

particular sequences of movements