Meeting Abstract
The reduced hindwings of flies, known as halteres, are specialized mechanosensory organs that detect inertial forces associated with body rotation during flight. Previous studies have shown that primary afferents of the haltere encode its oscillation frequency linearly over a wide bandwidth and with precise phase dependent spiking. It is not currently known whether information from haltere primary afferent neurons is sent to higher brain centers, or whether precise spike timing is useful beyond the peripheral circuits that drive wing movements. We show that in cells in the central brain, the timing and rates of neural spiking can be modulated by sensory input from the haltere. Using multichannel extracellular recording in a restrained flesh fly (Sarcophaga), we examined responses of central complex (CX) cells to a range of externally imposed haltere oscillation frequencies and visual motion speeds. Haltere-responsive units fell into multiple response classes, including those with firing rates linearly related to the haltere frequency and others with responses independent of frequency. We also investigated the responses of CX units when the fly was stimulated with both haltere oscillations and visual motion. Units that responded to both stimulus types when presented independently showed higher firing rates when both stimuli were presented simultaneously. Multimodal responses in these cells either varied with haltere frequency, independent of visual speed, or were sensitive to a narrow range of stimulus parameter combinations. Although haltere inputs have largely been studied in the context of rapid locomotion control, we have found haltere sensory information in a brain region known to be involved in slower, higher-order behaviors, such as navigation. This data, along with recordings from tethered walking animals, may indicate a role in behaviors that take place over a longer timescale.
