Figure 2. Transient effect of GABA microinjections on cardiac cells in a traditional open-loop protocol with periodic stimulation.

The top panel shows the effect of GABA on the membrane potential of a CPG neuron from the cardiac ganglion of Carcinus maenas. The vertical arrow indicates the instant in which a burst of periodic GABA microinjections (vertical lines) of 50 ms of duration and separated by 200 ms takes place. These injections produce a transient inhibitory effect on the bursting activity. The bottom panel is a blow up of the squared region on the top panel. Single pulses evoke a much more transient response as shown in Fig. 4, which is used to control the number of spikes in each burst during the closed-loop experiment.