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J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2005 May;191(5):435-44. Epub 2005 Mar 19.

Pedal neuron 3 serves a significant role in effecting turning during crawling by the marine slug Tritonia diomedea (Bergh).

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Division of Neuroscience, The University of Edinburgh, Appleton Tower, level 7, Edinburgh, EH8 9LE, UK.


The marine nudibranch Tritonia diomedea crawls using its ciliated foot surface as the sole means of propulsion. Turning while crawling involves raising a small portion of the lateral foot margin on the side of the turn. The cilia in the lifted area no longer contribute to propulsion, and this asymmetry in thrust turns the animal towards the lifted side. Neurons located in the pedal ganglia of the brain contribute to these foot margin contractions. T. diomedea has a natural tendency to turn upstream (rheotaxis), and pedal flexion neuron Pedal 3 elicits foot margin lift and receives modulatory input from flow receptors. To assess the contribution of this single cell in turning behavior, two fine wires were glued to the surface of the brain over left and right Pedal 3. We determined that Pedal 3 activity is correlated with subsequent ipsilateral turns, preceding the lift of the foot margin and the change in orientation by a consistent interval. Both Pedal 3 cells show synchronous bursts of activity, and the firing frequency of the ipsilateral Pedal 3 increased before turns were observed to that side. Stimulation of the electrode over Pedal 3 proved sufficient to elicit an ipsilateral turn in Tritonia.

[Indexed for MEDLINE]

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