Fig. 3. Electric field potentials recorded with bath electrodes during tail-flips. (A) An example trace of a tail-flip in response to a slow shadow. The action potential of the medial giant neuron (MG, asterisks; magnified in the inset) can be seen and enables non-ambiguous identification of the tail-flip as mediated by giant neuron activity. The large deflections that follow are field potentials generated by simultaneous muscle contractions caused by the giant spike. (B) A second example trace of a tail-flip in response to a slow shadow that is followed 43 ms later by a second tail-flip. The action potential of the MG neuron (asterisks; magnified in the inset) can be seen for the first tail-flip while the much smaller and less phasic potential for the second tail-flip is characteristic of field potentials caused by activity in the non-giant (Non-G; black arrow) circuit. See text for further explanation.