The neuroscience of adaptive thermoregulation.

The nervous system acts as a biological thermostat by controlling behaviors that regulate the warming and cooling of animals. We review the structures responsible for thermoregulation in three model species: roundworms (Caenorhabditis elegans), flies (Drosophila melanogaster), and rats (Rattus novegicus). We then consider additional features of the nervous system required to explain adaptive plasticity of the set-point temperature and the precision of thermoregulation. Because animals use resources such as energy, water, and oxygen to thermoregulate, the nervous system monitors the abundance of these resources and adjusts the strategy of thermoregulation accordingly. Starvation, dehydration, or hypoxemia alter the activity of temperature-sensitive neurons in the pre-optic area of the hypothalamus. Other regions of the brain work in conjunction with the hypothalamus to promote adaptive plasticity of thermoregulation. For example, the amygdala likely inhibits neurons of the pre-optic area, overriding thermoregulation when a risk of predation or a threat of aggression exists. Moreover, the hippocampus enables an animal to remember microhabitats that enable safe and effective thermoregulation. In ectothermic animals, such as C. elegans and D. melanogaster, the nervous system can alter set-point temperatures as the environmental temperatures change. To build on this knowledge, neuroscientists can use experimental evolution to study adaptation of neural phenotypes in controlled thermal environments. A microevolutionary perspective would leverage our understanding of ecological processes to predict the origin and maintenance of neural phenotypes by natural selection.