alien hand syndrome
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alien hand syndromeA disorder in which a person’s hand or limb acts as if it has autonomous, voluntary activity independent of the individual. For example, the hand which is under the person’s normal voluntary control might put a cigarette in the mouth, and the alien hand might knock it out.
The reason for alien hand syndrome is unknown; it is thought that the primary motor cortex controlling hand movement is isolated from influences of the premotor cortex, but is still able to execute hand movements. Neuroimaging of patients with alien hand syndrome typically reveals lesions in the medial frontal lobe and corpus callosum. There is no cure or treatment.