From Notices of the AMS
Rate-Based Synaptic Plasticity Rules
by Lawrence Udeigwe
Communicated by Reza Malek-Madani
Introduction
The human nervous system is made up of networks containing billions of nerve cells also known as neurons. These networks function as a result of each neuron transmitting electrochemical signals to nearby neurons when it releases an action potential or spike. This spike occurs when the difference in electrical potential between the inside and outside of the neuron, also known as its membrane potential, exceeds a certain threshold (see Figure 1 [7]). Increase in membrane potential is elicited by several factors including inputs from other neurons and the environment. The frequency at which a neuron spikes is referred to as its spike rate or activity rate or firing rate. The firing rate and firing pattern of a neuron encodes a good amount of the information it transmits.
At the moment a neuron spikes, an electrical pulse travels from the cell body down the axon fiber to be received by nearby neurons whose dendrites are connected to its axon ends. The junction where the axon head meets a dendrite is known as a synapse. The neuron transmitting the signal is called the presynaptic neuron and the neuron receiving the signal is called the postsynaptic neuron (see Figure 2).
