Proceedings of the National Academy of Sciences | 2019
Temporal signals underlying a cognitive process in the dorsal premotor cortex
Abstract
Significance When trained monkeys discriminate between two sequential vibrotactile stimulus patterns, neurons in the dorsal premotor cortex (DPC) code current and remembered inputs and the commands expressing the decision report. Additionally, responses of these neurons and neurons with no coding responses also reflect the timing of the task sequence. What is the cognitive relevance of these time-dependent signals? We show that time-dependent signals reflected the temporal sequence of the task during both hits and error trials but diminished or disappeared during a nondemanding cognitive task that did not require discrimination for reward. Also, strong links were detected between neuronal population and individual neurons’ time-dependent signals. These time-dependent responses may function as the substrate network dynamics on which task coding components emerge. During discrimination between two sequential vibrotactile stimulus patterns, the primate dorsal premotor cortex (DPC) neurons exhibit a complex repertoire of coding dynamics associated with the working memory, comparison, and decision components of this task. In addition, these neurons and neurons with no coding responses show complex strong fluctuations in their firing rate associated with the temporal sequence of task events. Here, to make sense of this temporal complexity, we extracted the temporal signals that were latent in the population. We found a strong link between the individual and population response, suggesting a common neural substrate. Notably, in contrast to coding dynamics, these time-dependent responses were unaffected during error trials. However, in a nondemanding task in which monkeys did not require discrimination for reward, these time-dependent signals were largely reduced and changed. These results suggest that temporal dynamics in DPC reflect the underlying cognitive processes of this task.