Meeting Abstract

P3.104  Wednesday, Jan. 6  Correlation of the activity of novel pedal neurons and body flexion in the sea slug Tritonia diomedea ZAZAY, R*; MURRAY, JA; George Washington U.; Cal. State. U. East Bay; Friday Harbor Labs james.murray@csueastbay.edu

There have been 16 pairs of identified cells in the pedal ganglion of Tritonia diomedea. The pedal neurons cause flexion of the ipsilateral body wall and foot when activated, but they probably do not innervate muscle directly. We recorded the activity two new cells and their motor effects. We first made the cells stop firing by injecting them with negative current. Once the cell stopped firing, we injected it with positive current via an amplifier. In one ~100 micron wide cell, the animal lifted one side of its foot and when the current stopped it relaxed it. The cell had one axon exiting Pedal Nerve 1 and about nine dendrites coming off of it. When the cell was stimulated the front half of the foot would move dorsally and posteriorly ~ 1 cm. As the muscle relaxed, the front of the foot moved ventrally and the back of the foot had moved more posteriorly. The stimulated spikes lasted for 13 seconds and there was an approximate 3 second delay between the initial spike and the foot movement of the slug. The muscle took about 4 seconds to start relaxing and then it fully relaxed after 10 seconds. In a second cell (150 µm soma) in a different animal, the dorsal body wall flexed medially when current was injected. It had one axon in Pedal Nerve 4 and few dendrites coming off the axon. When the cell was stimulated, the animal would flex its dorsal body wall medially, then relax. The stimulated spikes lasted for 10 seconds and there was a 3 second delay before body movement. It took about 6 seconds to start relaxation after spikes ended, and then after 15 seconds it fully relaxed. Even though the cell relaxed it did not return to its original point. These pedal neurons may be involved in turning during crawling and we will follow these experiments with fine wire recordings from crawling slugs to determine behavioral function.