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Are release phenomena explained by disinhibited mirror neuron circuits?: Arnold Pick's remarks on echographia and their relevance for modern cognitive neuroscience.
Berthier, M. L., PULVERMULLER, F., Green, C. & Higueras, C
Aphasiology, 20(5), 462-480
Year of publication:
Background : Echographia, an extremely rare syndrome first described by Pick (1900, 1924), is characterised by automatic translation of visual and sometimes also auditory stimuli into writing. Little information is available about surface symptoms, pathological correlates, and functional mechanisms of this syndrome. Aims : We here review Pick's original case description of echographia and contrast its surface symptoms and neuropathological correlates with more recently described single cases. We then set out to propose a new theoretical framework for the understanding of echographia which is inspired by contemporary research, including experimental studies in monkeys and neurophysiological and brain-imaging studies in humans. Main Contribution : Arnold Pick described a patient with severe aphasia after large left perisylvian (frontotemporal) infarction who showed a surprising ability to copy written words that were familiar to her, but no foreign words. Pick believed that the elicitation of echographia by written material resulted from a combination of reflexes and voluntary processes. He suggested that circumscribed damage to the left temporal lobe produced the release of this sort of uncontrolled motor behaviour, and in the present article it is suggested that the involvement of the perisylvian language cortex precluded its full expression. Echographia in modern cases was seen to both written and auditory stimuli, coexisted with incessant writing activity and other environmental-induced behaviours, and was associated with lesions in the medial frontal and temporal lobes. It is argued that echographia and copious writing in these modern cases represent forms of imitation and utilisation behaviours selective for writing skills which result from relative sparing of fronto-parietal circuits including audiovisual mirror neurons that control writing actions. Conclusions : Pick's original description of echographia represents the earliest example of utilisation behaviour selective for writing skills. This historical case illuminates the current understanding of the so-called environmental-induced behaviours by revealing that such abnormal behaviours can be modality specific. Credit is also given to Pick for integrating audiovisual perception and action in the production of writing, for taking into consideration the permissive role of writing acquisition in the emergence of echographia after brain damage, and for recognising that echographia resulted from released activity of spared parts of the damaged brain.