Voltammetry In Vivo for Chemical Analysis of the Living Brain
Published Online: 15 SEP 2006
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
O'Neill, R. D. and Lowry, J. P. 2006. Voltammetry In Vivo for Chemical Analysis of the Living Brain. Encyclopedia of Analytical Chemistry. .
- Published Online: 15 SEP 2006
The mammalian brain is the most complex structure known to science. Our behavior, feelings, thoughts, and maybe even consciousness itself, may be a reflection of the interplay of electrical and chemical signaling that create these states, and how the physical brain gives rise to the properties of mind remains a major unanswered question. It is clear, however, that many of the drugs used empirically in the treatment of neurological disorders, such as Parkinson's disease, schizophrenia and depression, as well as mind-altering substances of abuse, have specific chemical actions on nerve cells in the brain, highlighting the importance of chemical signaling in the functioning of neural networks.
A growing number of methodologies are being developed, including sampling, spectroscopic and electrochemical, to study neurochemical phenomena in the living brain. One such set of techniques focuses on the detection of substances released from nerve cells, using amperometric electrodes and voltammetry in vivo (VIV) techniques. By implanting a microvoltametric electrode in a specific brain region, applying a suitable potential profile and recording the resulting faradaic current, changes in the concentration of a variety of substances in the extracellular fluid (ECF) can be monitored with sub-second time resolution over extended periods. This allows investigations of the functions and roles of specific neurochemicals in neuronal signaling, drug actions, and well-defined behaviors. The main limitations associated with VIV is, on the one hand, the limited number of ECF species that are electroactive, and on the other, the fact that electroactive substances present tend to oxidize at similar potentials, interfering with each other's detection. These restrictions are being overcome by ongoing developments, including the design of biosensors to broaden the range of target analytes and permselective membranes to block interference.