Cortical control of movement

Question 1

How can the 3 main cortical motor regions be identified?

Answer 1

1) Neurons increase their firing rates before movements and specific features of this activity are often closely related to specific movement features
2) Neurons send their axons to terminate in motor centres in the brainstem and spinal cord
3) Electrical stimulation in these areas elicits movement
4) Neurones send their axons to connect most densely with other motor areas

Question 2

What does the primary motor cortex do?

Answer 2

Neurones in the primary motor cortex have a simple relationship to movement. They fire around 5 to 100 Ms before movement onset and can code for the basic parameters of movement, i.e.:
* Force
* Extent
* Direction
* Speed

Question 3

What is the relationship between neurones in the non-primary motor cortex and movement

Answer 3

They code for more complex aspects of movement (than those in primary motor cortex)

E.g., pre-motor cortex - code for more complex parameters of movement like planning movement and spatial guidance of movement

Question 4

What does the supplementary motor cortex do?

Answer 4

Neurones in the supplementary motor cortex code other complex aspects of movement that are different to those in the pre-motor cortex. E.g., bimanual control

Question 5

What is the corticospinal tract and what are its origins?

Answer 5

The most important tract in the human for precise control of limbs
Origin:
30% - Primary motor cortex
30% -Premotor cortex, supplementary
40% - Somatosensory