Neural dynamics of reaching following incorrect, absent, or last-moment preparation
Abstract/Contents
- Abstract
- Moving is thought to require separate preparation and execution steps. While preparing, neural activity in primary motor and dorsal premotor cortices achieves a state specific to an upcoming action, but movements are not performed until the execution phase. In this work, we investigated the interactions between motor preparation and motor execution. We first investigated whether the preparatory state (more precisely, prepare-and-hold state) is required for movement execution using two complementary experiments. We compared monkeys' neural activity during delayed and non-delayed reaches, and in a delayed reaching task in which the target switched locations on a small percentage of trials. Neural population activity bypassed the prepare-and-hold state both in the absence of a delay and if the wrong reach was prepared. However, the initial neural response to the target was similar across behavioral conditions, regardless of whether there was a delay period. This means that there are consistent neural preparatory steps which are performed prior to movement even in the absence of a delay. This suggests that the prepare-and-hold state can be bypassed if needed, but there is a short-latency preparatory step which is performed prior to movement even without a delay. We suggest that this preparatory step may be best understood as a dynamical process rather than simply a particular, static neural state. We next examined whether motor preparation and motor generation can be run in parallel. We instructed monkeys to reach to a particular target, and occasionally switched that target to a new location shortly before the monkey began initiating his reach. We found that the amount of time required to change a reach goal tends to remain constant regardless of whether that computation is being performed online (during the execution of the initially-cued reach), or offline (prior to reach initiation). Examining neural activity during this task, we found that neural activity following a switch tends to explore dimensions which are not well-represented during the course of normal reaching. Furthermore, reaches can be initiated correctly even if their neural activity has not fully recovered from the switch, as long as neural activity in dimensions which are relevant to movement output has been corrected. This work reveals a potentially important way in which neural activity can simultaneously prepare one reach while executing another, again underscoring the view that motor preparation is itself a dynamical process which is independent of but complimentary to movement generation.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2014 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Ames, Katherine Cora |
|---|---|
| Associated with | Stanford University, Neurosciences Program. |
| Primary advisor | Shenoy, Krishna V. (Krishna Vaughn) |
| Thesis advisor | Shenoy, Krishna V. (Krishna Vaughn) |
| Thesis advisor | Ganguli, Surya, 1977- |
| Thesis advisor | Newsome, William T |
| Thesis advisor | Raymond, Jennifer L |
| Advisor | Ganguli, Surya, 1977- |
| Advisor | Newsome, William T |
| Advisor | Raymond, Jennifer L |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Katherine Cora Ames. |
|---|---|
| Note | Submitted to the Program in Neuroscience. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2014. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2014 by Katherine Cora Ames
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