Perseveration refers to any continuation or recurrence of activity without appropriate stimulus (cf. intrusions). Perseverations may be repeated motor behaviors (e.g., drawing, writing) or speech. These are viewed as a failure to inhibit a previous response pattern. Sensory perseveration is also described, e.g., palinopsia in the visual system.
A number of varieties of perseveration have been described, associated with lesions in different areas of the brain:
Inappropriate maintenance of a current category or framework; thought to reflect a deficit in executive function; associated with frontal lobe (especially frontal convexity) damage, which is associated with an inert, apathetic pattern of behavior, rather than the disinhibited pattern associated with orbitofrontal damage.
Unintentional repetition of a previous response to a subsequent stimulus; thought to represent an abnormal postfacilitation of a memory trace; associated with posterior left (dominant) hemisphere damage; commonly seen in aphasics, Alzheimer’s disease; this overlaps with "intrusions."
Inappropriate prolongation or repetition of a current behavior without interruption; thought to represent a deficit of motor output; associated with basal ganglia damage.
Hudson AJ. Perseveration. Brain 1968; 91: 571-582
Sandson J, Albert ML. Varieties of perseveration. Neuropsychologia
1984; 22: 715-732