Meeting Abstract

P3.100  Wednesday, Jan. 6  Biologically realistic limb coordination during walking in the absence of central connections between legs RINEHART, Marc D.*; BELANGER, Jim H.; West Virginia University; West Virginia University jim.belanger@mail.wvu.edu

Neuronal control of interlimb coordination during walking is not fully understood. Load and position cues are thought to influence stepping coordination between legs, but it is unclear if central connections between legs are required. To test this, we created a crayfish model in the simulation environment AnimatLab. In the model, all legs are identical, and receive sensory feedback from three sources: position sensors at each joint, a contact sensor at the dactyl, and a load sensor. All legs are driven by individual oscillators. That is, all legs function independently of each other with no direct connections between the legs. The model can produce realistic walking behavior without load feedback. The only sensory cue that is necessary is from the contact sensors. In walking simulations, legs nearest the center of mass showed a preferred coordination with ipsilateral and contralateral neighbors. Legs farther away from the center of mass displayed more variability in coordination. Contact information was also sufficient to change the characteristics of leg oscillations, i.e. cycle periods and stance durations. We also tested the effects of limb amputations. In intact models, coordination between adjacent ipsilateral legs is predominantly alternating. After amputation of a leg, the two intact neighboring legs assume an alternating coordination. These results are very similar to those observed in actual crayfish. These findings suggest that interlimb coordination in multi-legged animals does not have to be integrated into the dedicated neuronal network that produces walking. Instead, coordination can be an indirect result of the coupling of individual leg oscillators through the environment.