Structure and function of pedal neurons controlling muscle contractions in Tritonia diomedea

California State University East Bay, Hayward, California

There are 16 pairs of "identified neurons" in the pedal ganglion of any sea slug of the species Tritonia diomedea that have published behavioral functions. Many of the pedal neurons cause flexion of the ipsilateral body wall and foot when activated, but they are not thought to innervate muscle directly. The goal of this study was to examine the motor functions of brain neurons with no previously-identified functions. We described the activity of two such cells and their motor effects, and further characterized the motor effects of a previously-identified neuron (Pedal 3). We stimulated the Pedal 3 flexion neuron and characterized where and how it contracted the foot. For each neuron, we described the latency to contraction, the time to relaxation, and the distance and speed of movement. These neurons may be involved in turning during crawling, and these results will help us understand how the activity of specific neurons is translated into behavior (neuromechanics), and determine how fast the animal can respond to sensory feedback during locomotion. The relative simplicity of this brain allows us to understand how behavior is generated on a cellular basis, and to generate neural network and neuromechanical models of navigation that can be applied to robotics.

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