Animals maintain optimal core body temperatures under changing ambient conditions by adjusting energy expenditure, heat generation, and physical activity. Studies have implicated temperature-sensitive neurons in regions of the brain’s hypothalamus called the preoptic area (POA) and dorsomedial hypothalamus (DMH) in body temperature control. However, the underlying neural pathways remain imprecisely identified.

Researchers report that exposing mice to 38 ºC for 2 hours induced the activation of a subset of neurons in the ventral portion of the lateral preoptic nucleus (vLPO), which is located in the POA, and the dorsal portion of the DMH (DMD). Triggering or tamping down the activity of vLPO neurons using optogenetic tools resulted in reduced and fever-level body temperatures, respectively.

The vLPO neurons are connected to and act upon DMD neurons, which were found to be activated by cold, to raise body temperature, and to induce physical activity when stimulated using molecular tools.
The authors pinpoint a subset of DMD neurons, mostly GABAergic DMD neurons, as heat generators. Importantly, GABAergic vLPO neurons countervailed the activity of DMD neurons to reduce heat generation and maintain core body temperature.

According to the authors, the findings uncover a previously unreported neural circuit involved in body temperature maintenance, which is a vital homeostatic function.

http://www.pnas.org/content/early/2017/01/03/1616255114