Meeting Abstract
Insects collect and process information from their environment using a host of sensory modalities to maintain control during flight. While vision is necessary for flight, the precision, sensitivity, and rapid processing speeds of mechanoreceptors relative to vision make that modality a critical component, particularly in response to perturbations. Furthermore, previous anatomical and behavioral evidence confirms that the wings of the hawkmoth Manduca sexta could inform the animal of its body dynamics, much like halteres do for dipteran flies. But, the features of mechanosensory stimuli, their timing, and the precision with which those stimuli are encoded by wing mechanoreceptors remain relatively unexplored. Using multi-site extracellular electrophysiology along with white-noise mechanical stimulation, spike sorting algorithms, and methods from computational neuroscience we characterized the encoding properties of wing mechanoreceptors in the hawkmoth. We focused on two key aspects of encoding: the average stimulus feature (the spike triggered average: STA) and the non-linear decision function (NDF). The STA is derived from the ensemble of stimuli that yield spikes in any one sensory neuron. The latter is a measure of the probability of spiking given any arbitrary stimulus. We measured the STA and NDF for 32 identified neurons from 16 moths. We found (1) nearly all STAs show a very rapid response with their peaks occurring less than 5 ms prior to a spike (2) the shape of the STA varies in manner consistent with those identified for haltere neurons and (3) the NDF shows that mechanoreceptors are extremely selective for the temporal pattern of the stimulus. These results are similar to those found for halteres in Diptera. Unlike halteres, however, wings serve the dual roles of sensing and actuation.
