Meeting Abstract

P2.145  Monday, Jan. 5  Inactivation of an identified neuron reduces oriented turning toward the inactivated side in the sea slug Tritonia diomedea SHERMAN, AJ*; MURRAY, JA; TRAN, NB; HAMMOUDI, AH; Cal. State. U. East Bay; Cal. State. U. East Bay; U. Washington; U. Central Arkansas james.murray@mac.com

The nudibranch mollusk Tritonia diomedea has been used extensively to study the neural control of orientation behavior. Many of its ~7000 neurons have been established as having specific functions and are reidentifiable from one animal to another. One specific pair of neurons, Pedal neurons #3 (Pd3), receive modulatory input from water flow receptors, elicit contractions of the ipsilateral foot margin, and are thus believed to be involved in rheotactic turning behavior. Pd3 has been shown to increase in firing frequency during turning, and stimulation of Pd3 with fine wires stimulates ipsilateral turns. This study aims to determine if Pd3 is necessary for turning behavior by inactivation in either or both ganglia. If Pd3 is necessary for turning, then experimental animals will fail to turn upstream into water flow and control animals will remain able to so after the semi-intact preparation. Inactivation of right Pd3 (RPd3) resulted in the animal failing to crawl upstream, but instead continually turned left. Similarly, inactivation of left Pd3 (LPd3) resulted in the animal continually turning right.. Preliminary observations indicate that turning events involve different body positioning; these movements are likely due to the effects of other pedal flexion neurons. Inactivation of Pd3 may result in the use of other neurons involved in lifting the foot margin to achieve a turning event. Kinematic analysis illustrates how and to what extent turning behavior is modified by ablation of Pd3. These results, together with those demonstrating that Pd3 is sufficient for turning, further our understanding of the sensorimotor processes involved in orientation behavior and how they are integrated to guide the animal through its habitat.