FIG. 1.
A: measurement of transient phase response curves (PRCs) with a spiking neuron of Aplysia californica. The period of the membrane potential (top trace) of the spiking neuron changed due to the injected current (bottom trace) changing at time ts after the onset of the spike. P1 and P2 illustrate the period of the perturbed cycle and of the following cycle, respectively. B: measuring functional PRCs (fPRCs) in an experiment using spiking neurons of Aplysia californica with excitatory input with parameters of maximum conductance gsyn = 0.04 μS and time constant τ = 10 ms. The distance between the dots above the voltage trace indicates the interspike intervals (ISIs) along the process of the experiment. The bottom trace indicates the time course of the current injected into the neuron; the blue trace illustrates the unperturbed neuron intrinsically firing action potentials; the red trace illustrates the periodic perturbations to make an fPRC measurement; and the green traces show the intrinsic firing of the unperturbed neuron after the stimulation is turned off. C: time sequence of ISIs for the specific fixed-delay time in B. The blue and green dots indicate the ISIs before and after repetitive stimuli; the red dots indicate the ISI being perturbed; the cyan star indicates the value of the fixed-delay time and the time when the repetitive stimulus is turned on.