Fig. 2

Dendritic spatial summation and signal propagation of neuro-transistors. a, c Input signals and circuit diagrams. The red and blue curves represent the “pre-synaptic” voltage spikes to two capacitive synapses. The DPM serves as the gate of the neuro-transistor with two capacitively-coupled fixed-weight synapses S₁ and S₂. b, d The triggered gate potential, representing the membrane potential of a biological neuron, and the drain current, corresponding to the axon current of the neuro-transistor, depicted by the black and green curves, respectively. In the case that a single synapse was excited, the resultant stimulation could not trigger output pulses. However, concurrent stimulation of both synapses produced clear temporal integration on the neuro-transistor gate and the associated spikes in the output current. e Circuit diagram of cascaded neuro-transistors N₁ (n-MOSFET) and N₂ (p-MOSFET). Fixed capacitance synapses were used with equal weights (680 pF). f The first stage N₁ integrated the fixed-frequency input signal 1 (blue line) and fired periodically (black and red lines), with some variation in the integration time. g The voltage to the second stage N₂ was the weighted sum of the voltage on S₁ resulting from the output of N₁ and the input signal 2 (blue line), with the resulting N₂ gate potential (black line) and the second stage output current (red line) shown. The firing of the second stage neuro-transistor N₂ illustrates both spatial summation and sustainable signal propagation