Neural Circuits & Behavior Process Report // Vahid Esmaeili - Learning-induced involvement of cortical areas during a whisker-based short-term memory task

Execution of goal-directed behaviors involves coordination of a distributed network of cortical regions. How different brain areas encode different aspects of behavior and how these representations change upon learning remains to be elucidated. To address this, we devised a Go/No-go task in which head-fixed mice detect a brief whisker deflection to collect a reward. A visual cue signals the beginning of each trial. Upon whisker stimulation, mice need to withhold licking during a post-stimulus delay until an auditory go-cue is presented. This delay period separates sensory processing from action initiation, allowing us to investigate which brain areas contribute to sensory detection and action planning.
We performed silicon probe recordings in multiple brain areas while Expert or Novice mice performed the task. Upon whisker stimulation, a short-latency response appeared with a sequential order in primary somatosensory cortex (wS1) and secondary somatosensory cortex (wS2) followed by primary (wM1) and secondary motor cortex (wM2) in both Expert and Novice mice. Anterior lateral motor cortex (ALM), tongue/jaw motor cortex (tjM1) and posterior parietal cortex (PPC) represented the whisker stimulus with longer latencies and their activity bridged the delay period in Expert but not in Novice mice. ALM and tjM1 transiently signaled initiation of licking earlier than other areas. Optogenetic inhibition during specific behavioral epochs revealed distinct involvement of cortical areas. Our data thus defines global and local entrainment of different cortical areas upon learning of a short-term memory goal-directed behavior