Task-induced modulations of neuronal activity along the auditory pathway

Sensory processing varies depending on behavioral context. Here, we ask
how task-engagement modulates neurons in the auditory system. We train
mice in a simple tone-detection task, and compare 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 reveals
widespread modulations across all regions and cortical layers, and in both
putative regular and fast-spiking cortical neurons. Clustering analysis
unveils ten distinct modulation patterns that can either enhance or
suppress neuronal activity. Task-engagement changes the tone-onset
response in most neurons. Such modulations first emerge in subcortical
areas, ruling out cortical feedback as the only mechanism underlying
subcortical modulations. Half the neurons additionally display 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.