Workshop 4 Description:

Workshop 4: Neuromechanics of Locomotion
Organizers: Philip J. Holmes, Robert J. Full, and Ansgar Bueschges

Workshop 4 focuses on the question of how animals are deceptively simple. They push against the world, with legs, fins, tails, wings, or their whole bodies, and the rest is Newton's third and second laws. But of course locomotion emerges from complex interactions among animals' neural, sensory and motor systems, their muscle-body dynamics, and their environments. Three broad approaches reflect this:

1) Neurobiology has successfully studied the role of central pattern generators (CPGs) in the control of locomotion. CPGs are networks of neurons that can generate muscular activity in the absense of sensory feedback. By its action, the nervous system can generate a basic neural output that can signal the muscles when to contract. In this mode, the nervous system tells the muscles what to do and muscles pass the message on to limbs, which move the body.

2) A closely related approach concentrates on proprioceptive feedback in intralimb and interlimb coordination for shaping locomotory patterns. Thus, what the limbs are doing now, tells them what to do next.

3) Biomechanical studies focus on body-limb-environment dynamics and often ignore neural detail. Thus, Newtonian mechanics, with (mostly) passively-generated forces, tell the body what it must do.

All three approaches have generated rich mathematical models of individual neurons and circuits, sensory pathways and state estimators, and body-limb mechanics. Further mathematical modeling, at various spatial and temporal scales, can play a central role in synthesizing these approaches into neuromechanical descriptions of locomotion. Thus, Hodgkin-Huxley meets Newton with A.V. Hill as matchmaker.

This workshop, and the closely-related ones on muscle biomechanics (Workshop 2) and neuroengineering (Workshop 5) will emphasize the development of integrative models. The major mathematical tools will include dynamical systems, stochastic ODE, control theory, and (non-)classical mechanics with intermittent contacts and impacts in running and walking, and unsteady fluid mechanics in swimming and flight.