Lsens LAB, Brain Mind Institute, EPFL, Suisse

Cortical contributions to context-dependent goal-directed sensorimotor transformation

Flexible integration of sensory information in a context-dependent manner is a key cognitive process required to generate appropriate behavior. An intriguing question, then, is how the same sensory stimulus can be interpreted differently according to context in order to generate different behavioral responses. We designed a task in which thirsty head-restrained mice were trained to lick for a water reward in response to a brief single whisker stimulus if it was preceded by a brief Go-tone presented one second before the whisker stimulus, but not if it was preceded by a NoGo-tone. Optogenetic inactivation of primary whisker somatosensory cortex (wS1), secondary whisker somatosensory cortex (wS2), secondary whisker motor cortex (wM2), or anterior lateral motor cortex (ALM) during the presentation of the whisker stimulus strongly decreased the probability of licking in the reward window in Go-trials. Inactivation of wM2 and ALM during the delay between the Go-tone and the whisker stimulus also strongly reduced licking in the reward window. We recorded neuronal activity in auditory cortex (A1), wS1, wS2, wM2 and ALM using multiple Neuropixels probes simultaneously. Prominent persistent activity following the Go-tone presentation was found selectively in wM2 and ALM, even in trials devoid of delay period movements. Using linear decoding of neuronal activity, we found that the accuracy of classifying context in the 200 ms before the whisker stimulus was significantly higher than the baseline chance level, with the highest accuracy in wM2 and ALM. Temporal correlation analysis showed that the contextual information was maintained in frontal areas through stable persistent activity. Consistently, it was possible to classify context with high accuracy from the neuronal activity of wM2 and ALM, throughout the delay period, using a classifier trained only on the last 200 ms of the delay period. These findings suggest a crucial role for the frontal areas wM2 and ALM in the encoding and maintenance of contextual information in a short-term memory task. In ongoing analyses, we aim to determine which classes of neurons in wM2 and ALM are most involved in context coding, how neurons in different cortical regions interact, and how the context-dependent delay period activity gates the transformation of whisker deflection-evoked sensory responses into licking motor initiation signals to obtain reward.

Invité par Isabelle Férézou