A thalamic inhibitory circuit aligns sensory coding with learned value
Adaptive behavior requires sensory systems to prioritize cues that predict meaningful outcomes while suppressing irrelevant stimuli, but how relevance-based filtering is implemented along early sensory pathways remains unclear. Using deep brain two-photon imaging and causal circuit manipulations in mice performing an audiovisual detection task, we show that inhibition from thalamic reticular nucleus dynamically tunes sensory thalamus according to learned value. As animals learned stimulus-outcome associations, neurons in medial geniculate body developed biased responses favoring reward-predicting cues and suppressing non-rewarded stimuli. Silencing inhibitory input from thalamic reticular nucleus broadly disinhibited thalamic responses and abolished this value bias. Notably, stimulus identity decoding was unaffected by loss of inhibition. However, the geometry of MGB population activity was reorganized: coding axes rotated, action-related coding was strongly impaired, and thalamic representations became misaligned with learned behavioral readout. This altered population code impaired behavioral performance despite preserved sensory separability. Thus, inhibition of sensory thalamus by the reticular nucleus does not simply gate sensory throughput; it acts as a subcortical coding mechanism that aligns neuronal representations with learned value and behavioral goals, with implications for disorders of perception and cognition.