Meeting Abstract
The Drosophila larva executes a stereotypical exploratory routine in which it appears to alternate between straight peristaltic crawling and lateral turning events. Contemporary explanations for this behaviour have relied upon putative central pattern generating and decision-making circuits within the larval brain. Taking a novel approach, we have developed a model of larval mechanics which describes axial and transverse motion over a planar substrate, and have used it to postulate a simple, reflexive neuromuscular model based on physical principles. Through principled mechanical analysis, we show that peristaltic crawling may be seen as a natural consequence of the body’s tendency to propagate axial elastic waves, while turning results from an energetic coupling between axial and transverse motions which allows peristaltic waves to drive turning motions. Furthermore, this coupling causes the motion of the body to become chaotic and unpredictable, giving rise to spontaneous “transitions” between peristalsis and turning. At a population level, this encourages a view of exploration as an emergent deterministic superdiffusion process which is mechanistically grounded in the physics of the body. Indeed, our neural models do not function as decision makers or pattern generators, but rather as amplifiers or filters for sensory feedback; they selectively emphasize patterns which are already present within the dynamics of the body. Most strikingly, the coupling of axial and transverse degrees of freedom means that an entire exploratory routine can be produced without any explicit sensing or control of turning, and without any decisions regarding when to transition between behavioural states.
