The Japanese journal of neuropsychology

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ArticleTitle	Lesions around insula causing limb apraxia
Language	J
AuthorList	Masaki Kondo
Affiliation	Department of Neurology, Kyoto Prefectural University of Medicine
Publication	Japanese Journal of Neuropsychology: 30 (1), 41-48, 2014
Received
Accepted
Abstract	In this article, I overview lesions causing limb apraxia and the history of apraxia studies, and discuss the association between apraxia, the insula, and areas around the insula. Firstly, I introduce the case of a 61-year-old right-handed male with degenerative dementia, who exhibited impaired semantic memory and object use. Brain imaging showed atrophy and low-level perfusion in the insula and surrounding areas, with a predominance in the left hemisphere. Secondly, I overview several attractive schemata for apraxia. In Liepmann's schema, the movement formulae are produced in the left temporo-parieto-occipital junction (TPO) and transferred anteriorly to the sensorimotor region (central area). In Geschwind's schema, the origin of action control is moved from the TPO to Wernicke's area. The disconnection between Wernicke's and the premotor area is an important cause of apraxia. Inferior parietal lesions cause apraxia when they encroach upon the arcuate fasciculus. In Heilman's schema, parietal lesions disrupt the movement formulae themselves. Movement formulae are stored in the angular and supramarginal gyrus and transferred via the premotor to motor area. Thirdly, I mention the association between apraxia and other systems such as the mirror-neuron system, two or more streams concerned with actions, involving the basal ganglia. The mirror-neuron system is considered to be activated on both performing an action and on observing the same action performed by another. The inferior parietal lobe and premotor area overlap in the mirror-neuron system and apraxia schemata. Spatial information-processing in the dorsal occipitoparieto-frontal stream and semantic information-processing in the ventral temporo-occipitoparietal stream are assumed to be integrated when actions are generated and controlled. Lesions in the basal ganglia were reported to cause apraxia, and lesions were frequently reported in the left hemisphere and accompanied by surrounding white matter. The type of apraxia caused by lesions of the basal ganglia is likely to be ideomotor apraxia. Moreover, some studies analyzed movement disorder of the arm and hand in patients with Parkinson's disease, a neurodegerative disease affecting the basal ganglia, from the viewpoint of apraxia. Although apraxia caused by an insular lesion per se has rarely been reported, lesions in areas around the insula have been reported to be a cause. The areas around the insula, which include the premotor area, central area, Broca's area, basal ganglia, and inferior parietal lobe, could comprise a network associated with apraxia.
Keywords	limb apraxia, insula, apraxia schema, mirror neuron system, basal ganglia