Does an ecologically-relevant odor influence visual motion selectivity in the hawkmoth nerve cord


SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY
2021 VIRTUAL ANNUAL MEETING (VAM)
January 3 – Febuary 28, 2021

Meeting Abstract


93-1  Sat Jan 2  Does an ecologically-relevant odor influence visual motion selectivity in the hawkmoth nerve cord? Gage, S*; Aiello, BA; Sharma, V; Sprayberry, J; Sponberg, S; Georgia Tech ; Georgia Tech ; Georgia Tech ; Muhlenburg College; Georgia Tech sgage7@gatech.edu

The behavioral context of an animal can modulate visual processing. First observed in primates, and recently in flies and mice, attention and locomotion modify visual neuron tuning curves by increasing spike rates and shifting curves to higher frequencies. These changes may enable animals to better process rapidly changing visual scenes associated with motion compared to quiescence. We wondered whether sensory context, specifically the addition of an ecologically-relevant odor, could similarly affect how neurons respond to visual motion. We considered the crepuscular hawkmoth, Manduca sexta; which relies on both vision and olfaction to locate and forage from flowers, a process that transitions from flight navigation to hover feeding. We hypothesized that the tuning curve of wide-field motion (WFM) units would increase overall firing rate and shift towards higher frequencies; and that responsiveness to oscillating flowers would also increase with odor. To test these ideas, we recorded from ventral nerve cord neurons downstream of sensory integration centers in the brain. Using a multi-channel electrode, we established responses to WFM and flower stimuli, followed by a floral odor known to elicit innate odor responses. Odor enhanced the firing rate of WFM responsive units and shifted the peak of the tuning curve 1-2 Hz higher. Some direction-sensitive units also began to respond in the opposing direction. Flower-responsive units showed increased firing rates. In some units, however, odor inhibited responses to both types of visual motion. This change in gain and selectivity may suggest that odor functions as a “fine tuner” during navigation and hovering. Odor may refine visual tuning for close flower tracking and other rapidly moving, near-field objects during foraging.

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