ABSTRACT
For many years, subtle alterations in brain function that are associated with exposure to
neurotoxic substances have been a central focus of research interest. These alterations,
occurring in the absence of a clinically identifiable intoxication or encephalopathy, are
important because they are the first indicators that a substance is adversely affecting the
brain. Research into subtle toxicant-induced brain damage using behavioral outcome
measures has been critical in identifying these early neurotoxicant effects. The use of
neuroimaging technology has played a role in identifying the structural effects of exposure
to toxicants resulting in clinical manifestations of intoxication, especially in substances
such as carbon monoxide (1-3) and mercury (4,5). However, until recently imaging
technology had limited capability for identifying subtle alterations in brain structure
and function.
