Fig. 2.

Diagrammatic representation of the experimental method used to establish the blocking dose of TTX on the femoral nerve. Bipolar-stimulating electrodes placed on each of the two ventral roots that supply the motor fibers in the femoral nerve were stimulated supramaximally, and the evoked action potential was recorded on the femoral nerve distal to the application of TTX to the nerve. Doses of 60 mg/ml were found to be effective in completely blocking action potential conduction (see the text for further details).VR, Ventral root.