Synaptic inhibition in the lateral habenula shapes reward anticipation

The nervous system can associate neutral cues with rewards to promote appetitive adaptive behaviors. The lateral habenula (LHb) contributes to such behaviors as rewards and reward-predictive cues inhibit this structure and engage LHb-to-dopamine circuits. However, the mechanistic understanding of reward encoding within the LHb remains unknown. We report that, in mice, acquisition of anticipatory licking in a reward-conditioning task potentiates postsynaptic GABAergic transmission, leaving excitatory synapses unaffected. Conversely, LHb-targeted manipulations of postsynaptic GABAergic function via pharmacological blockade or impairment of GABAA receptor trafficking decrease anticipatory licking. Hence, inhibitory signaling within LHb enables the expression of appetitive behaviors.