Meeting Abstract

P2.186  Thursday, Jan. 5  Do Bullfrogs Tune Forelimb Muscle Activity in Anticipation of Landing? HICKS, Rebecca*; KATZ, Hilary; MACESIC, Laura J.; GILLIS, Gary B.; Mount Holyoke College; Mount Holyoke College; Mount Holyoke College; Mount Holyoke College ggillis@mtholyoke.edu

Landing from a fall or jump generally requires coordinated, anticipatory activation of limb muscles. For example, in a variety of mammalian species, including cats and humans, both the timing and intensity of pre-landing muscle activity in ankle extensors are modulated in relation to the expected impact. Similarly, recent work with hopping toads (Bufo marinus) has shown that the onset timing and pre-landing recruitment intensity of elbow antagonists vary predictably with hop distance. To test if such landing preparation is unique to toads among anurans, we studied muscle activity patterns in elbow antagonists in bullfrogs (Rana catesbiana). Electromyographic recordings were made in the coracoradialis, an elbow flexor, and the lateral head of the anconeus, an elbow extensor, during hops of varying distance. Particular attention was paid to the average signal intensity in the 50 ms before landing and to the onset timing of activity. Results reveal that like cane toads, bullfrogs modulate pre-landing forelimb muscle activity patterns depending the expected time and magnitude of impact. Hops in which animals are in the air longer, and presumably hit the ground harder, lead to more intense pre-landing activity in both elbow antagonists. Moreover, onset timing in the anconeus tracks the time of impact, so as to consistently begin approximately 100 ms before landing, regardless of the aerial phase duration. Our data suggest that tuning forelimb muscle activity to landing is not unique to toads and is more widespread among anurans.