Figure 3. Activity-dependent drug microinjection.

Panel A shows a schematic representation of the closed-loop drug stimulation protocol. In this example, the membrane potential of a neuron is monitored by an event detection algorithm to perform the activity-dependent drug microinjection. When an event is detected, the software sends a signal to the microinjector and the neurotransmitter or neuromodulator is released. Panel B shows the real time (RT) stimulation protocol we employed in the experiments discussed in this section. This adaptive protocol consists of a double 1 mM GABA injection (two 40 ms pulses separated by 30 ms) when the third spike is detected at the beginning of a burst of a cardiac neuron (vertical lines indicate the detection of single spikes, arrows indicate the instant in which the microinjection takes place). The resulting inhibitory closed-loop is used to achieve a desired number of spikes in the bursting activity of these neurons.