Meeting Abstract
112.6 Tuesday, Jan. 7 11:30 Motor patterns of aquatic and terrestrial escape responses in the mangrove rivulus (Kryptolebias marmoratus) PERLMAN, B.M.*; ASHLEY-ROSS, M.A.; Wake Forest University; Wake Forest University perlbm0@wfu.edu
The aquatic C-start escape response in teleost fishes is driven by a well-studied network of reticulospinal neurons that produce a stereotyped muscle activation pattern of simultaneous contraction of axial muscle along the body on the side away from the stimulus, followed by a traveling wave of contraction on the contralateral side. Superficially, the kinematics of the terrestrial tail-flip resemble the aquatic C-start, with the anterior body rolling up and over the tail into a tight C shape, followed by straightening as the fish launches off of the caudal peduncle into ballistic flight. We asked if similar motor control is used for both behaviors in K. marmoratus, the mangrove rivulus. Four fine-wire bipolar electrodes were percutaneously inserted into repeatable locations in four individual fish: paired (left and right sides) anterior epaxial muscle, right posterior lateralis superficialis muscle, and in the body cavity to act as a ground. Electromyographic recordings synchronized with high-speed video (500 fps) were made of aquatic C-starts in a 10-gallon tank, immediately followed by terrestrial tail-flips. Motor patterns in both environments were grossly similar, with muscle ipsilateral to the concave side of the bend activating first, followed by contralateral muscle(s) activating after a delay. Tail-flips took longer to complete than aquatic escape responses; muscles were activated for longer durations on land. Differences also exist in specific features of the motor pattern: in the tail-flip, activity was seen in posterior axial muscle contralateral to the bend during the formation of the C shape, likely to press the caudal peduncle against the ground in preparation for launch. Thus, the tail-flip is not simply a C-start performed on land, but represents a distinct locomotor behavior.
