Selective Suppression of Local Circuits during Movement Preparation in the Mouse Motor Cortex

Prepared movements are more efficient than those that are not prepared for. Although changes in cortical activity have been observed prior to a forthcoming action, the circuits involved in motor preparation remain unclear. Here, we use in vivo two-photon calcium imaging to uncover changes in the motor cortex during variable waiting periods prior to a forepaw reaching task in mice. Consistent with previous reports, we observed a subset of neurons with increased activity during the waiting period; however, these neurons did not account for the degree of preparation as defined by reaction time (RT). Instead, the suppression of activity of distinct neurons in the same cortical area better accounts for RT. This suppression of neural activity resulted in a distinct and reproducible pattern when mice were well prepared. Thus, the selective suppression of network activity in the motor cortex may be a key feature of prepared movements. [Display omitted] •We developed a reaching task to model motor preparation in mice•A distinct group of motor cortex neurons increased activity during a waiting period•Other motor cortex neurons suppressed activity during a preparation period•Specific patterns of circuit activity and suppression accompany motor preparation After establishing a delayed reaching task in mice, Hasegawa et al. identify a specific pattern of motor circuit activity during motor preparation. These circuit activity patterns are mediated by the suppression of a majority of neurons in the motor cortex and may be important contributors to motor preparation.