Meeting Abstract

13.3  Thursday, Jan. 3  Comparison of Jumping and Feeding in the Northern Leopard Frog, Rana pipiens ESSNER, JR., R.L.*; TOENNIES, J.L.; SUFFIAN, D.J.; Southern Illinois University Edwardsville; Southern Illinois University Edwardsville; Southern Illinois University Edwardsville ressner@siue.edu

Similarities in motor patterns, kinematics, and kinetics among such diverse behaviors as hopping, jumping, and swimming suggest that the neural control of locomotion in frogs is relatively simple yet versatile. Feeding (lunging) is also characterized by synchronous hind limb extension and may be controlled in a similar manner. We tested this hypothesis by filming Northern Leopard Frogs (Rana pipiens) jumping and feeding with an integrated setup consisting of high-speed video (250 Hz) and electromyography on six muscles (semimembranosus (hip extensor); gracilis major (hind limb extensor); plantaris longus (hind limb extensor); coccygeoiliacus (epaxial); longissimus dorsi (epaxial); and anconeus (forelimb extensor)). Both jumping and feeding were characterized by simultaneous onset of all muscles examined, followed by periods of low-level activity. Durations of muscle activity did not differ significantly for five of six muscles with the notable exception of the anconeus, which was active for significantly longer during feeding. Mean amplitudes of EMG bursts were significantly higher during jumping for five of six muscles, again with the exception of the anconeus. Changes in muscle amplitude between feeding and jumping varied by muscle, with the greatest increase occurring in the plantaris (factor of 4.5). Based on these results, we propose that 1) forelimb control is to some degree decoupled from that of other elements; and 2) the determining factor for jumping and feeding is the amplitude of individual muscles rather than the timing of muscle activation.