Learning-related population dynamics in the auditory thalamus

Learning to associate sensory stimuli with a chosen action has been classically attributed to the cortex. Whether the thalamus, considered mainly as an upstream area relative to cortex, encodes learning-related information is still largely unknown. We studied learning-related activity in the dorsal and medial regions of the medial geniculate body (MGB), part of the non-lemniscal auditory pathway. Using fiber photometry, we continuously imaged population calcium dynamics as mice learned a go/no-go auditory discrimination task. The MGB was tuned to frequency shortly after stimulus onset and responded to cognitive features like the choice of the mouse several hundred milliseconds later. Encoding of choice in the MGB increased with learning, and was highly correlated with the learning curves of the mice. MGB also encoded motor parameters of the mouse during the task. These results provide evidence that the MGB encodes task- motor- and learning-related information.