Fig. 2
From: Perspective on photonic memristive neuromorphic computing
a Diagram of the biological neuron highlighting the main components of the cell, the connection between axon and dendrite and the direction of signal propagation (red arrows). Reproduced with permission of© 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece. b Schematic illustration of McCulloch and Pitts model. The model consists of N inputs (IN) multiplied by corresponding N weights (wN), which are summed together (∑). The activation function (φ(∙)) evaluates the sum of the inputs and if a threshold is reached, the neuron will send its output signal. c Schematic illustration of an implementation of the leaky-integrate-and-fire (LIF) model. The four functional blocks are input, state, leak, and action potential. Combined in a circuit, they integrate linearly the input, exhibit a constant leakage, and emit a spiking signal when the potential crosses a threshold. In this way they implement an integrate-and-fire neuron. Reproduced from ref. [12] with permission