Meeting Abstract
To understand how odors affect a fly’s locomotion, as well as the role of various olfactory neurons, we made two innovations: 1) we created an arena in which a fly’s locomotion could be studied under precisely controlled stimulus condition. 2) we created a generative model for a fly’s locomotion. We discovered that a fly’s locomotion can be decomposed into discrete units, called locomotor features. Odors affect locomotion by altering the fraction of time that a fly spends performing each locomotor feature. The effect of odors on locomotor features is modular: each odor activates multiple olfactory neurons, and a different (but overlapping) subset of neurons affects each locomotor feature. We also investigated the role of two brain regions, the mushroom body (MB) and lateral horn (LH) in odor modulation of locomotion. Based on preliminary experiments, we hypothesize that: 1) LH mediates sensorimotor transformation linking the presence of a particular odor to a particular locomotor parameter, 2) MB combines the ongoing sensory experience with current demands and stimulus history to modulate locomotion. We present preliminary evidence that supports this hypothesis: These evidences come from experiments in which we activated and inactivated small populations of MBONs and LHONs to assess their effect on behavior. Another line of evidence come from recording from MBONs and LHONs to evaluate how they encode sensory input and motor output. Our findings have significance beyond olfaction. Our finding of modularity underlying complex behavior has important implications for how complex behaviors are executed by the brain. Moreover, locomotor features describe how behavior is organized over 10-300 steps. To our knowledge, this is the only quantitative description of the control of locomotion on this relatively long timescale.
