Perseveration refers to the inappropriate continuation or repetition o
f a response or activity. It is associated with a variety of neurologi
cal disorders and, when pronounced, is thought to be pathognomonic of
brain damage. Perseveration manifests itself in several different form
s which have had various labels applied, and many hypotheses have been
proposed to explain the mechanisms underlying these perseverative beh
aviours. In this article we review descriptions and classifications of
preservation as it occurs in various neurological disorders, and then
discuss some of the neurobehavioural and neuropathological mechanisms
thought to account for it.