Time for Action: Neural Basis of the Costs and Benefits of Temporal Predictability for Competing Response Choices

摘要

The brain can anticipate the time of imminent events to optimizesensorimotor processing. Yet, there can be behavioral costsof temporal predictability under situations of response conflict.Here, we sought to identify the neural basis of these costs andbenefits by examining motor control processes in a combinedEEG–EMG study. We recorded electrophysiological markers ofresponse activation and inhibition over motor cortex when theonset-time of visual targets could be predicted, or not, and whenresponses necessitated conflict resolution, or not. If stimuli weretemporally predictable but evoked conflicting responses, weobserved increased intertrial consistency in the delta range overthe motor cortex involved in response implementation, perhapsreflecting increased response difficulty. More importantly, temporalpredictability differentially modulated motor cortex activityas a function of response conflict before the response was eveninitiated. This effect occurred in the hemisphere ipsilateral to theresponse, which is involved in inhibiting unwanted actions. Iftarget features all triggered the same response, temporal predictabilityincreased cortical inhibition of the incorrect responsehand. Conversely, if different target features triggered twoconflicting responses, temporal predictability decreased inhibitionof the incorrect, yet prepotent, response. This dissociationreconciles the well-established behavioral benefits of temporalpredictability for nonconflicting responses as well as its costsfor conflicting ones by providing an elegant mechanism thatoperates selectively over the motor cortex involved in suppressinginappropriate actions just before response initiation.Taken together, our results demonstrate that temporal informationdifferentially guides motor activity depending on responsechoice complexity.