Task-induced modulations of neuronal activity along the auditory pathway
Sensory processing varies depending on behavioral context. Here, we asked how task-engagement modulates neurons in the auditory system. We trained mice in a simple tone-detection task, and compared their neuronal activity during passive hearing and active listening. Electrophysiological extracellular recordings in the inferior colliculus, medial geniculate body, primary auditory cortex and anterior auditory field revealed widespread modulations across all regions and cortical layers, and in both putative regular and fast-spiking cortical neurons. Clustering analysis unveiled ten distinct modulation patterns that could either enhance or suppress neuronal activity. Task-engagement changed the tone-onset response in most neurons. Such modulations first emerged in subcortical areas, ruling out cortical feedback from primary auditory areas as the only mechanism underlying subcortical modulations. Half the neurons additionally displayed late modulations associated with licking, arousal or reward. Our results reveal the presence of functionally distinct subclasses of neurons, differentially sensitive to specific task-related variables but anatomically distributed along the auditory pathway.