How does alien hand syndrome work?
Alien hand syndrome is a unusual neurological scenario, by which one hand (almost always the left) conducts actions with out conscious administration of the actual individual affected (it can in all probability moreover impact the left leg). Victims frequently remark that one other individual is transferring their hand, or that it is transferring by itself. They may even be unaware of the alien hand’s actions until one factor attracts their consideration to it.
The most common cause behind alien hand syndrome is damage to the corpus callosum – the part of the thoughts that serves because the one connection between the two hemispheres. Whereas this can be the outcomes of strokes or totally different thoughts damage, severance of the corpus callosum has been a typical remedy for excessive epilepsy. When the two hemispheres cannot speak, they each act as separate entities. Each hemisphere controls the hand on the choice aspect of the physique, and when not associated each can form differing opinions, and will act upon them independently. However, when such a person speaks, only one hemisphere is mainly speaking, as a result of the speech centres are located throughout the left hemisphere. This ends in the impression that the actions undertaken by the left hand aren't beneath administration – the entity controlling them is solely mute, and might't justify its actions.
One other conditions might result in alien hand syndrome.
One-sided damage to mesial parts of the frontal lobe may trigger exploratory reaching actions throughout the corresponding hand, the place stretching in course of and grasping shut by objects is bolstered by way of a tactile optimistic ideas loop (usually often called magnetic apraxia). It could be troublesome to extract the merchandise from the affected hand as quickly as this has occurred.
Hurt to posterior sections of the thoughts (notably the inferior parietal lobule) may trigger one different distinct variant of alien hand syndrome. The affected hand avoids touching objects, and will withdraw in anticipation of points coming into contact with it.