Hot on the trail of temperature processing

Two studies investigate how information about temperature is processed in the brains of fruit flies, and reveal that different neuronal pathways transmit heating and cooling signals to higher brain regions. See Letters p.353 & p.358 Animals detect changes in external temperatures via thermoreceptors in the peripheral nervous system, but the central circuits that then process such signals have been unknown. Now two studies, led by Rachel Wilson and Marco Gallio, report distinct classes of neurons in the fly brain, which respond to external cooling, warming, or both, and contribute to behavioural response. The results illustrate how higher brain centres extract the quality, intensity and timing of a stimulus from a simple temperature map at the periphery.