Meeting Abstract
The nervous system of a behaving animal must be able to distinguish sensory signals arising from its own movement from sensory signals arising from the environment. This is accomplished by modulating sensory input via a corollary discharge circuit (CDC), which relays information from motor networks to the relevant sensory circuits. Visual-, auditory-, and proprioceptor-motor CDCs have previously been described in many systems, but until recently, olfactory-motor CDCs were unknown. In moths, a pair of mesothoracic-deutocerebral histaminergic neurons (MDHns) project from flight sensorimotor centers in the mesothoracic neuromere to the antennal lobes (ALs). We recently demonstrated that MDHn spiking activity is correlated with wingbeat motor output, and application of histamine to the MDHns sharpens AL projection neuron entrainment to odor stimuli. Likewise, application of a histamine H2 receptor antagonist reduces projection neuron entrainment and inhibits odor detection and discrimination. Here we test the effects of blocking the MDHn circuit on a moth’s ability to track an odor plume in a wind tunnel. Cimetidine (an H2 receptor antagonist) or saline vehicle was injected bilaterally into the ALs of tobacco hornworm moth (Manduca sexta) males. Cimetidine-injected moths successfully tracked sex pheromone plumes, but their flight dynamics were significantly different than controls: cimetidine-injected moths flew slower, had smaller course angles, and had longer inter-turn durations than controls. These results are consistent with the observed effects of H2 receptor antagonists on reduced preparations.
