Getting our heads around the brain
Glossary
axon. An extension of a nerve cell that transmits nerve impulses to other cells.
electrode. An electrical conductor. Electrochemical reactions occur on the surface of an electrode.
An electrode can be used to deliver electricity to the body or to receive electricity from it. Delivering electricity to the body is used to stimulate; receiving electricity from the body can be used to detect and record signals. In either case the term refers to the contact formed by the stimulating or recording device within the body.
grey matter. The tissue of the nervous system that appears greyish because of the relatively high proportion of nerve cell nuclei that occur there. This is in contrast to white matter which consists mainly of axons. It appears whitish because of the insulating lipid-protein sheath around axons. Photomicrographs of grey matter and white matter can be found at a site from the Department of Anatomy and Cell Biology at the University of Kansas, USA.
neurotransmitter.A chemical substance, given off by the ends of the axon of a nerve cell or nerve fibre which allows a message to be passed between different links in the chain. It is the arrival of the electrical impulse at the end of the nerve fibre that causes the release of a neurotransmitter into the small gap (called the synapse) between nerve cells. The neurotransmitter travels across the synapse and excites or inhibits the next nerve cell in the chain.
radioisotope. A form of an element that spontaneously disintegrates into other substances and emits small particles (radiation or radioactivity). The presence and movement of the radioisotope in the body can be detected by monitoring the emission of the small particles.
Posted May 1998.