Imitation behavior is the reproduction by the patient of gestures (echopraxia) and/or utterances (echolalia) made by the examiner in front of the patient; these "echophenomena" are made by the patient without preliminary instructions to do so. They are consistent and have a compulsive quality to them, perhaps triggered by the equivocal nature of the situation. There may be accompanying primitive reflexes, particularly the grasp reflex, and sometimes utilization behavior.
Imitation behavior occurs with frontal lobe damage; originally mediobasal disease was thought the anatomical correlate, but more recent studies suggest upper medial and lateral frontal cortex. Certainly imitation behavior never occurs with retrorolandic cortical lesions.
A distinction has been drawn between "naïve" imitation behavior, which ceases after a direct instruction from the examiner not to imitate his/her gestures, which may be seen in some normal individuals; and "obstinate" imitation behavior which continues despite an instruction to stop; the latter is said to be exclusive to frontotemporal dementia.
De Renzi E, Cavalleri F, Facchini S. Imitation and utilisation behavior. Journal of Neurology, Neurosurgery and Psychiatry 1996; 61: 396-400 Lhermitte F, Pillon B, Serdaru M. Human autonomy and the frontal lobes. Part I: imitation and utilization behavior: a neuropsychological study of 75 patients. Annals of Neurology 1986; 19: 326-334 Shimomura T, Mori E. Obstinate imitation behavior in differentiation of frontotemporal dementia from Alzheimer’s disease. Lancet 1998; 352: 623-624