title: Intersegmental coupling and recovery from perturbations in freely running cockroaches.
abstract: Cockroaches are remarkably stable runners, exhibiting rapid recovery from external perturbations. To uncover the mechanisms behind this important behavioral trait, we recorded leg kinematics of freely running animals in both undisturbed and perturbed trials. Functional coupling underlying inter-leg coordination was monitored before and during localized perturbations, which were applied to single legs via magnetic impulses. The resulting transient effects on all legs and the recovery times to normal pre-perturbation kinematics were studied. We estimated coupling architecture and strength by fitting experimental data to a six-leg-unit phase oscillator model. Using maximum-likelihood techniques, we found that a network with nearest-neighbor inter-leg coupling best fitted the data and that, although coupling strengths vary among preparations, the overall inputs entering each leg are approximately balanced and consistent. Simulations of models with different coupling strengths encountering perturbations suggest that the coupling schemes estimated from our experiments allow animals relatively fast and uniform recoveries from perturbations.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University, NJ 08544, USA Department of Zoology, Tel Aviv University, Tel Aviv 6997801, Israel einat@princeton.edu.
authors.forename: Einat
authors.initials: E
authors.lastname: Couzin-Fuchs
authors.affiliation: Department of Kinesiology, University of Maryland, College Park, MD 20742, USA.
authors.forename: Tim
authors.initials: T
authors.lastname: Kiemel
authors.affiliation: Department of Zoology, Tel Aviv University, Tel Aviv 6997801, Israel.
authors.forename: Omer
authors.initials: O
authors.lastname: Gal
authors.affiliation: Department of Zoology, Tel Aviv University, Tel Aviv 6997801, Israel Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.
authors.forename: Amir
authors.initials: A
authors.lastname: Ayali
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University, NJ 08544, USA Program in Applied and Computational Mathematics and Princeton Neuroscience Institute, Princeton University, NJ 08544, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Holmes
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003058:Cockroaches / Q000502:physiology*; D005121:Extremities / Q000502:physiology*; D012420:Running
keywords: Central pattern generator; Intersegmental coordination; Leg perturbation; Locomotion; Phase oscillators