Nerve impulses from primary motor cortex can cause movement even when person is unaware

Alien hand syndrome (AHS) is a rare neurological disorder that causes hand movement without the person being aware of what is happening or having control over the action. The afflicted person may sometimes reach for objects and manipulate them without wanting to do so, even to the point of having to use the healthy hand to restrain the alien hand. A new study identified the areas of the brain involved in both voluntary and involuntary movement and found that neural activity was restricted to the primary motor cortex during the unconscious motor activity seen with AHS. The study will be published online in the Annals of Neurology (http://www.interscience.wiley.com/journal/ana), the official journal of the American Neurological Association.