Featured Paper of the Month – April 2018.
The lateral habenula (LHb) is a brain structure that participates in cognitive and emotional processing and has been implicated in several mental disorders. Although one of the largest inputs to the LHb originates in the lateral preoptic area (LPO), little is known about how the LPO participates in the regulation of LHb function. In their recent study, Barker and colleagues provide evidence that the LPO exerts bivalent control over the LHb through the convergent transmission of excitatory LPO glutamate and inhibitory LPO g-aminobutyric acid (GABA) onto single LHb neurons. In vivo, both LPO-glutamatergic and LPO-GABAergic inputs to the LHb are activated by aversive stimuli, and their predictive cues yet produce opposing aversive or rewarding behaviors when stimulated independently. These results support a model wherein the balanced response of converging LPO-glutamate and LPO-GABA are necessary for a normal response to noxious stimuli, and wherein an imbalance in LPO/LHb glutamate or GABA may result in the type of aberrant processing that underlies mental disorders such as drug addiction.