Primary Motor Cortex at Root of Alien Hand Syndrome

Rare disorder involves more selective activation of brain than voluntary movement

WEDNESDAY, July 18 (HealthDay News) -- The rare neurological condition known as alien hand syndrome, in which a patient involuntary moves his or her hand and may even pick up and manipulate objects without will, is associated with selective activation of the primary motor cortex, researchers report in the July issue of the Annals of Neurology.

Frédéric Assal, M.D., of the University Hospital in Geneva, Switzerland, and colleagues present a case study of a 70-year-old right-handed man who experienced a large stroke in the right parietal lobe and subsequently developed alien hand syndrome.

Functional magnetic resonance imaging of his brain taken while he performed simple motor tasks both voluntarily and involuntarily with the left hand revealed that involuntary tasks selectively activated the contralateral primary motor cortex, while voluntary movements activated the contralateral right motor cortex, the premotor cortex and the left inferior frontal gyrus.

While the primary motor cortex "may code for limb movement planned by parietal systems, only activity in the latter (but not the former) may mediate conscious experience of motor intentions," the authors write. "These data open new perspectives for the comprehension of neurological and neuropsychiatric disorders associated with abnormal motor control or abnormal awareness of action, such as utilization behavior, phantom limb, anosognosia or delusions of control in schizophrenia," they conclude.

Full Text (subscription or payment may be required)

Physician's Briefing