Fig. 3: Neuromorphic emulation of the paradoxical effect confirms inhibition-stabilized regime.
a The paradoxical effect is a well known phenomena in cortical circuits. In the awake resting cortex of mice (upper figure), when inhibitory neurons are optogenetically activated, their firing rates (in red) show a paradoxical decrease in activity during the stimulation, indicative of an inhibition-stabilized network. Adapted from Sanzeni et al.21. Similar to the experimental case (bottom figure), numerical simulations of firing rate models with sufficient excitatory gain and balanced by inhibition show the paradoxical effect when the inhibitory population is excited via an external current. b The paradoxical effect can be demonstrated in analog neuromorphic circuits by applying a Poisson input of 250 Hz for 200 ms to the inhibitory units of networks converged to self-sustained activity via cross-homeostasis. The resulting decrease in the firing rate of the inhibitory units demonstrates that the on-chip network is in the inhibition-stabilized regime. No. of trials = 14; the shading around the lines represents the standard deviation in firing rate across trials.
