Meeting Abstract
Insects use wind cues to guide many behaviors. For example, in search of food or mates, insects will turn upwind upon encountering an attractive odor. This behavior relies on the animal’s ability to gauge wind direction. Flies detect wind direction using antennal mechanosensors that project to a brain region called the antennal mechanosensory and motor center (AMMC). We set out to understand how wind direction is encoded downstream of this primary processing center by using whole-cell electrophysiology and a novel stimulus paradigm. We have found that wind direction is encoded by at least two classes of neurons that project from the AMMC to a second-order wind processing center in the brain. These neurons each receive input from the ipsilateral antenna and show distinct direction tuning. Further, we have identified a novel set of putative third-order projection neurons that encode wind direction with greater dynamic range and discriminability than either of the two types of second-order neurons. We find that these neurons combine input from both antennae, and that bilateral input is critical for their large dynamic range and increased discriminability. Next, we analyzed antennal movements in response to directional wind stimuli and found that comparison of signals across the two antennae can resolve ambiguities in the signal from a single antenna, and improve discriminability in the region in front of the fly. We are currently testing a simple model for how third-order responses are generated based on these results using genetic manipulations and physiology. Lastly, we hope to elucidate the role of these neurons in wind-guided navigation through ongoing experiments using a walking behavioral assay and genetic silencing.
