Fig. 4: Characterization of the spiking neuron’s frequency response, linearity, and coincidence detection.

Firing rate of the organic spiking neuron as a function of input frequency for eight synaptic weight voltages under flat (solid) and tension-bent (dotted) conditions, for a excitatory and b inhibitory PCS synaptic circuits. The sigmoidal response demonstrates input-output nonlinearity characteristic of integrate-and-fire dynamics, modulated by synaptic weight and mechanical bending. c Linearity assessment using two excitatory synaptic inputs with fixed frequency and weight. Top: the train of pre-synaptic signal at 10 Hz. upper-middle and middle: neuron response to individual activation of synapse 1 and synapse 2. Lower-middle: response to simultaneous activation of both synapses. Bottom: Whisker plots indicate that the combined firing frequency (1.26 Hz) closely matches the linear sum of individual inputs (0.6 and 0.66 Hz), validating the neuron’s ability to linearly integrate temporally concurrent signals. d Coincidence detection characterization with two subthreshold presynaptic signals applied with increasing inter-stimulus intervals (ISIs). The red trace shows membrane potential dynamics during integration. Full dataset is available in Supplementary Fig. 19.