Sean A Spence1. 1. University of Sheffield, Academic Department of Psychiatry, The Longley Centre, UK. S.A.Spence@Sheffield.ac.uk
Abstract
INTRODUCTION: Alien motor phenomena arise in neurological and psychiatric contexts and are likely to implicate several distributed brain systems. METHOD: A selective literature review, focusing on cognitive neurobiological accounts of alien/anarchic limb, somatoparaphrenia, and delusions of alien control (passivity phenomena); supplemented by an account of the cognitive neuroanatomy of action and agency (subjective sense of causation) in the normal state. RESULTS: Alien motor phenomena reflect impairments of agency through at least two mechanisms. (1) A disinhibition of ''lower'' motor centres giving rise to relatively stereotypic and contextually inappropriate motor routines (as emerge following medial frontal and corpus callosal lesions). (2) A disturbance of the perception of self-initiated movement, so that control of movement (causation) is attributed to an alien entity (phenomena associated with right parietal lobe lesions, focal epilepsy, and hyperactivity in acute schizophrenia). CONCLUSION: Whereas alien/anarchic limb dysfunction may be relatively easily explained in cognitive neurobiological terms, a comprehensive account of alien control will require further empirical ingenuity. Current models invoke disturbed feed-forward mechanisms, imitation, and the sense of another's agency (''nonself attribution'').
INTRODUCTION:Alien motor phenomena arise in neurological and psychiatric contexts and are likely to implicate several distributed brain systems. METHOD: A selective literature review, focusing on cognitive neurobiological accounts of alien/anarchic limb, somatoparaphrenia, and delusions of alien control (passivity phenomena); supplemented by an account of the cognitive neuroanatomy of action and agency (subjective sense of causation) in the normal state. RESULTS:Alien motor phenomena reflect impairments of agency through at least two mechanisms. (1) A disinhibition of ''lower'' motor centres giving rise to relatively stereotypic and contextually inappropriate motor routines (as emerge following medial frontal and corpus callosal lesions). (2) A disturbance of the perception of self-initiated movement, so that control of movement (causation) is attributed to an alien entity (phenomena associated with right parietal lobe lesions, focal epilepsy, and hyperactivity in acute schizophrenia). CONCLUSION: Whereas alien/anarchic limb dysfunction may be relatively easily explained in cognitive neurobiological terms, a comprehensive account of alien control will require further empirical ingenuity. Current models invoke disturbed feed-forward mechanisms, imitation, and the sense of another's agency (''nonself attribution'').
Authors: Ganesan Venkatasubramanian; Dawn Thomas K Puthumana; Peruvumba N Jayakumar; B N Gangadhar Journal: Indian J Psychiatry Date: 2010-10 Impact factor: 1.759
Authors: Quinton Deeley; Eamonn Walsh; David A Oakley; Vaughan Bell; Cristina Koppel; Mitul A Mehta; Peter W Halligan Journal: PLoS One Date: 2013-10-21 Impact factor: 3.240