Meeting Abstract

75.3  Wednesday, Jan. 6  Gecko tails flip out: modulated motor control and variable movement following autotomy HIGHAM, T.E.*; RUSSELL, A.P.; Clemson University; University of Calgary thigham@clemson.edu

Many lizards are notable for their ability to self-amputate their tail during an encounter with a predator. The autotomized tail subsequently moves without control from higher centers and serves to distract the predator while the lizard escapes. Whereas the energetic, ecological and functional ramifications of tail loss for many lizards have been well-studied, little is known about the behavior and neuromuscular control of the autotomized tail. Once shed, the tail moves in ways not seen as an attached structure, indicating that suppressed movements are unleashed once the tail is severed. We used electromyography (EMG) and high-speed video to quantify the motor control and movement patterns of autotomized tails of leopard geckos (Eublepharis macularius). In addition to the movements immediately following autotomy, we quantified the changes in motor patterns and movements of tails until they stopped moving. We observed rhythmic swinging for the entire time following autotomy and complex movement patterns, including acrobatic flips up to 3cm in height, for only a brief time following autotomy. Unlike most central pattern generators (CPGs), muscular control of the tail is variable and can be arrhythmic. Although these complex patterns may arise in response to sensory information from the animal’s environment, multiple overlapping CPGs may also be responsible for such a pattern. The autotomized tails exhibited a decrease in mean spike amplitude, but an increase in burst duration as time elapsed following autotomy, suggesting that fast-twitch muscle fibers are being fatigued. We suggest that the gecko tail is well-suited for studies involving CPGs, given that this spinal preparation is naturally occurring, requires no surgery, and exhibits complex modulation