Is preparatory processing an essential component of voluntary movement? If so, when and how quickly does it occur?
It has long been known that neural activity can be present in motor and premotor cortex well before movement begins. What is the role of preparatory activity? Is it specific to the situation where a delay is artificially imposed, or is it an essential component of the normal sequence of voluntary movement?
We hypothesize that preparatory neural activity is essential to the generation of voluntary movement. Indeed, we hypothesize that movement-period dynamics will generate the appropriate movement only if the 'correct' preparatory state is achieved prior to movement onset.
Our recent discoveries have allowed us to test this hypothesis across a broad range of situations. Specifically, we find that preparatory and movement-related activity live in entirely separate and orthogonal neural subspaces (Elsayed et al. 2016). This allows us to test for the presence of preparatory activity even in the absence of a delay.
This allows us to ask: Is movement preparation essential to all, or only some, of these processes? Does it have a 'natural' time-course? How quickly can it occur? Is it possible to prepare while moving? When performing a sequence, are multiple movements prepared at once, or does preparation occur multiple times within the sequence?