Fan-Shaped Body Neurons in the Drosophila Brain Regulate Both Innate and Conditioned Nociceptive Avoidance

Abstract

Summary: Multiple brain regions respond to harmful nociceptive stimuli. However, it remains unclear as to whether behavioral avoidance of such stimuli can be modulated within the same or distinct brain networks. Here, we found subgroups of neurons localized within a well-defined brain region capable of mediating both innate and conditioned nociceptive avoidance in Drosophila. Neurons in the ventral, but not the dorsal, of the multiple-layer organized fan-shaped body (FB) are responsive to electric shock (ES). Silencing ES-responsive neurons, but not non-responsive neurons, leads to reduced avoidance of harmful stimuli, including ES and heat shock. Activating these neurons consistently triggers avoidance and can serve as an unconditional stimulus in an aversive classical conditioning task. Among the three groups of responsive neurons identified, two also have reduced activity in ES-conditioned odor avoidance. These results demonstrate that both innate and conditioned nociceptive avoidance might be represented within neurons confined to a single brain region. : Regulation of innate and conditioned nociceptive avoidance is critical for animal survival. Hu et al. find that neurons in the fan-shaped body, a multiple-layer organized brain region, are highly responsive to harmful stimuli, including electric shock, and can regulate both innate and conditioned avoidance of such stimuli in Drosophila. Keywords: Drosophila, fan-shaped body, nociception, innate avoidance, conditioned avoidance