Setup for closed-loop activity-dependent protocol.

<p>A–Experimental Setup. The EODs were measured using 8 electrodes, placed on the bottom of the tank (40×30×25) cm. The electrodes were connected to form an array of 5 dipoles: R-1R, R-2R and R-3R, sharing a common reference (R; white circles), A1-A2 (yellow circles) and B1-B2 (red circles). The signal from the 5 dipoles were differently amplified (gain = 50x or 100x: for small fish ~5 cm), summed, squared and then digitized at 25kHz by an ADC board (NI PCI-6521) and stored for posterior analysis. The stimulus pulses were generated by the same ADC board and controlled in real time by a closed-loop real time software that detected the EODs timing and delivered stimulus pulses in response. The stimulus pulses were delivered to the tank by a 7 cm dipole (artificial fish) to mimic an average size of <i>Gnathonemus petersii</i> used in this study. The artificial fish was placed in the middle of the tank as shown in the figure. B–Closed-loop activity-dependent protocol. The real time closed-loop software detected the EODs timing and sent a stimulus pulse after a time delay (<i>d)</i> chosen by the experimenter. The stimulus pulses had the exact <i>Gnathonemus petersii</i> waveform and 3V amplitude to mimic an average size animal. All experiments were performed with the same amplitude and wave shape.