Although I’ve taken a general interest in brain function and states of consciousness, until the last few years I really only paid much attention to the relationship between brain waves and states of consciousness, and in particular the use of brainwave entrainment methods to facilitate certain states (see earlier post here). Only in the last few years have I looked more closely into the complex and interacting roles of brain waves, neurotransmitters and various brain networks.

Neurons (nerve cells) in the brain form elaborate networks, with each neuron having up to 15,000 connections with neighbouring neurons at contact points called synapses. While the nerve impulse travel through the neuron as an electrical impulse, it does not cross the gap known as the synaptic cleft but rather stimulates the release of a chemical messenger: a neurotransmitter. This crosses the synaptic cleft and is received by neurotransmitter receptors on the target cell. A neurotransmitter with increase (excitatory) or decrease (inhibitory) the probability that the target cell will produce a nerve impulse.

There are three main types of neurotransmitters in the brain: small molecules used for fast signal transmission between neurons, small used for slower modulation of network activity, and large molecules (peptides) used for even slower modulation of cell circuit functions. Most neurons have receptors for most of the neurotransmitters in all three of these categories.