Fig. 2.

EOD-generating circuitry in Sternopygus. a The EOD is triggered by neurons of the pacemaker nucleus in the hindbrain, which activate the electric organ via b descending projections to spinal electromotor neurons. Each EOD pulse is the summation of the action potentials of the cells of the electric organ, the electrocytes. c Each action potential in the pacemaker nucleus is followed by a pulse from the electric organ. In a wave fish, such as Sternopygus, the pacemaker neurons of females discharge at a high rate and their electrocytes produce a brief action potential to generate a sinusoidal EOD at a high frequency. d The pacemaker neurons in males, on the other hand, fire at lower rates, and the EOD pulse is of longer duration to preserve the sinusoidal nature of the EOD (McAnelly and Zakon 2000)