NEURONAL CONNECTIVITY LINKING MOVEMENT PLANNING AND EXECUTION IN PREMOTOR CORTEX

The anterior lateral motor cortex (ALM) in mice is thought to play a central role in linking motor planning to execution. To understand the local circuit mechanisms underlying the transition from motor planning to execution, we here combine a virtual reality (VR) context-dependent directional licking task with 2-photon population imaging and holographic optogenetics.
We trained head-fixed mice to run along a virtual corridor for a water reward, with two different wall patterns signaling the rewarded lick direction in each trial (left or right). Mice rapidly learned to reduce running speed in anticipation of reward and to lick primarily on the rewarded side. Using 2-photon population imaging in ALM we find signature responses of ALM, including preparatory ramping activity and directionally selective activity related to motor execution. To test whether local connectivity could support the transition between movement planning and execution we probed the functional connectivity between ALM planning and execution neurons with an all-optical approach. To map functional connectivity between movement planning and execution neurons, we analyzed how the targeted activation of individual neurons with holographic stimulation influenced the activity of other neurons within the local network. We found both like-to-like as well as like-to-unlike coupling with preliminary results showing an asymmetric non-random influence between planning and execution neurons. These results support a model in which functionally distinct planning and execution ensembles are linked in a behaviorally meaningful manner.
Together, our all-optical approach combined with a VR-based directional licking task reveals circuit connectivity linking movement planning and execution in ALM.