The Largest Response Component in the Motor Cortex Reflects Movement Timing but Not Movement Type

Kaufman, M. T., Seely, J. S., Sussillo, D., Ryu, S. I., Shenoy, K. V., Churchland, M. M. (August 2016) The Largest Response Component in the Motor Cortex Reflects Movement Timing but Not Movement Type. eNeuro, 3 (4). ISSN 2373-2822 (Electronic)2373-2822 (Linking)

DOI: 10.1523/eneuro.0085-16.2016


Neural activity in monkey motor cortex (M1) and dorsal premotor cortex (PMd) can reflect a chosen movement well before that movement begins. The pattern of neural activity then changes profoundly just before movement onset. We considered the prediction, derived from formal considerations, that the transition from preparation to movement might be accompanied by a large overall change in the neural state that reflects when movement is made rather than which movement is made. Specifically, we examined "components" of the population response: time-varying patterns of activity from which each neuron's response is approximately composed. Amid the response complexity of individual M1 and PMd neurons, we identified robust response components that were "condition-invariant": their magnitude and time course were nearly identical regardless of reach direction or path. These condition-invariant response components occupied dimensions orthogonal to those occupied by the "tuned" response components. The largest condition-invariant component was much larger than any of the tuned components; i.e., it explained more of the structure in individual-neuron responses. This condition-invariant response component underwent a rapid change before movement onset. The timing of that change predicted most of the trial-by-trial variance in reaction time. Thus, although individual M1 and PMd neurons essentially always reflected which movement was made, the largest component of the population response reflected movement timing rather than movement type.

Item Type: Paper
Uncontrolled Keywords: condition-invariant signal dPCA movement initiation movement triggering reaction time state space
Subjects: organism description > animal behavior > decision making
organs, tissues, organelles, cell types and functions > tissues types and functions > motor cortex
CSHL Authors:
Communities: CSHL labs > Churchland lab
Depositing User: Matt Covey
Date: 30 August 2016
Date Deposited: 28 Oct 2016 14:54
Last Modified: 28 Oct 2016 14:54
PMCID: PMC5069299
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