An active whisker-dependent task to seek neuronal signatures of tactile sensory prediction in the mouse sensorimotor cortex
Résumé
Expectancy is an essential function of the nervous system, which allows the organism to react to the externalcontext in an effective way. Cortical circuits are thought to be involved in the computation of an internal model ofour interactions with the environment, which generate sensory expectations according to the context, past sensoryexperience, and current motor actions. According to predictive coding theories, in case of mismatch between suchexpectations and the actual experience, an error signal is generated, which is key to update the internal model andadjust the motor commands, thus optimising behaviour. To study the neuronal mechanisms underlying predictive coding in active conditions, we designed a new tactilesensorimotor task in which head-fixed mice are trained to contact several times a fixed object with a spared singlewhisker to obtain a reward. Then, during sessions performed with expert animals, we randomly interleave‘omission’ trials, in which the object is removed between two whisks, creating a deviance between expected andreceived tactile inputs. Using high-speed videography of the whisker behaviour, we study how the motor strategy evolves during thelearning process, and its rearrangement upon omission trials. Based on this behavioural protocol, which iscompatible with chronic and acute electrophysiological recordings, and with wide-field mesoscopic and two-photon optical imaging, we aim to better understand how the primary and secondary somatosensory cortices, ininteraction with the primary motor cortex, contribute to the construction of an internal representation of theobject, and the emergence of error signals.