1. (in biology) A circuit of interconnected neurons. All types of behaviour depend on information, in the form of nerve impulses, being transmitted via synapses between individual neurons (nerve cells) through neuronal networks. Such networks range from the relatively simple connections of a reflex arc (see reflex), to the highly complex circuits involved in processing information in the brain. However, their activity depends primarily on the number of constituent neurons and the configuration of their connecting synapses (e.g. excitatory or inhibitory). Most networks underlying complex behaviours include sensory and motor subcircuits that perform specific tasks, for example filtering sensory input or producing repetitive motor output (as in walking or swimming). Moreover, neuronal networks often exhibit plasticity, that is, they can be modified by experience.

2. (in information processing) A paradigm inspired by the organization and capabilities of neuronal networks, which can detect patterns and trends and exhibit adaptive learning. See synaptic plasticity.