What does an implant over the motor cortex read when a paralysed person intends to move? · Grey Matter

Neurons in motor cortex still fire with the intention to move even when the spinal cord or the muscles can no longer carry it out, and each neuron fires more for some directions or speeds than for others.

What does an implant over the motor cortex read when a paralysed person intends to move?

Neurons in motor cortex still fire with the intention to move even when the spinal cord or the muscles can no longer carry it out, and each neuron fires more for some directions or speeds than for others. An array recording a few hundred of them sees a pattern that changes with the intended movement, and a decoder trained while the person imagines or attempts moving maps that pattern onto a cursor's velocity, a click or, in the speech areas, the sounds a person tries to articulate. What it reads is intended movement, the output of planning, which is why these systems work best for actions the user tries to make.