Neuron
Neurons are the main functional unit of the brain and nervous system. They generate electrical signals called action potentials or "spikes" and transfer them to both other neurons and other cells, like muscles. Different kinds of neurons are differentiated by their form and
function, however, typically they bear the elements
illustrated in figure 1. One or various dendrites are connected to a circular shaped cell body (soma) housing the nucleus. Connected to it we see the tube shaped axon with multiple axon terminals at its end. The connection between an axon terminal of one neuron and a dendrite of another is called the synapse.Â
Via these electrochemicals connections one neuron is able to influence the electrical potential of another neuron, continuously following the same pattern: One neuron may be connected to multiple other neurons via synapses. The dendrites of that neuron thus collect input via the synapses in the form of spikes. These are gathered and summed at the neuron's soma. Once the summed input suffices to increase the neuron's electrical potential above a certain threshold level, that neuron generates a spike itself. This spike then follows the same journey down the axon to the various axon terminals, influencing other connected neurons via synapses. Using this connectivity pattern, whole populations of neurons form complex networks encoding information relevant for all cognitive and behavioral processes.
Figure 01: Broad illustration of a neuron and a synapse. Copied by hand from the Spektrum lexicon [https://www.spektrum.de/lexikon/psychologie/neuron/10516# accessed 29th of April, 18:00].
Source: Kolb, B., & Whishaw, I. Q. (2009). Fundamentals of human neuropsychology. Macmillan.
