RT Journal Article
SR Electronic
T1 Goal-directed action preparation in humans entails a mixture of corticospinal neural computations
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2024.07.08.602530
DO 10.1101/2024.07.08.602530
A1 Wadsley, Corey G.
A1 Nguyen, Thuan
A1 Horton, Chris
A1 Greenhouse, Ian
YR 2024
UL http://biorxiv.org/content/early/2024/07/11/2024.07.08.602530.abstract
AB The seemingly effortless ability of humans to transition from thinking about actions to initiating them relies on sculpting corticospinal output from primary motor cortex. This study tested whether canonical additive and multiplicative neural computations, well-described in sensory systems, generalize to the corticospinal pathway during human action preparation. We used non-invasive brain stimulation to measure corticospinal input-output across varying action preparation contexts during instructed-delay finger response tasks. Goal-directed action preparation was marked by increased multiplicative gain of corticospinal projections to task-relevant muscles and additive suppression of corticospinal projections to non-selected and task-irrelevant muscles. Individuals who modulated corticospinal gain to a greater extent were faster to initiate prepared responses. Our findings provide physiological evidence of combined additive suppression and gain modulation in the human motor system. We propose these computations support action preparation by enhancing the contrast between selected motor representations and surrounding background activity to facilitate response selection and execution.Significance statement Neural computations determine what information is transmitted through brain circuits. We investigated whether the motor system uses computations similar to those observed in sensory systems by noninvasively stimulating the corticospinal pathway in humans during movement preparation. We discovered that corticospinal projections to behaviorally relevant muscles exhibit nonlinear gain computations, while projections to behaviorally irrelevant muscles exhibit linear suppression. Notably, individuals with stronger signatures of these computations had faster motor responses. Our findings suggest that certain computational principles generalize to the human motor system and serve to enhance the contrast between relevant and background neural activity.Competing Interest StatementThe authors have declared no competing interest.