A neuron, or nerve cell, is a cell that sends and receives messages in the nervous system. It is through neurons that the brain communicates with every other part of the body.

1. dendrites - receive a message
2. soma - the body of the cell
3. axon - carries the message away from the cell
4. presynaptic terminals - release the message to be received by the next neuron.

Image Courtesy of Dr. Chudler of U. of Washington.

In between the presynaptic terminals of one neuron and the dendrites of another is the synapse. This is a gap into which the sending neuron emits special chemicals called neurotransmitters . The other neuron's dendrites receive these neurotransmitters.

Neurotransmitters related to memory:

• Acetylcholine is one of the most important memory neurotransmitters. It plays a major role in the laying down of memories, being transferred between the hippocampus and other parts of the nervous system. ["Alzheimer's Disease," 2000]
• Norepinephrine is related to the process of paying attention. (Benjamin, Hopkins, & Nation, 1994. p.284)
• Glutamateis another neurotransmitter involved in memory. It is received by the NMDA receptor. (Gorzelanczyk, 2000).

It is the pattern of the activation of neurons that create engrams, an important concept in memory.