A Brain of two Halves

Abstract

‘Your left hand doesn’t know what your right hand is doing’ is a saying used to convey the idea of disorganisation. Strangely, some people experience exactly that feelin_g because the part of their brain that knows what one hand is doin_g reall_y does not know what the other hand is doin_g. How could this be? The brain is divided into two relativel_y s_ymmetrical halves; the_y are onl_y relativel_y s_ymmetrical because althou_gh the_y look the same the_y have ver_y different functions. The split occurs from nose to back so the two halves are known as the ri_ght hemisphere and the left hemisphere. The_y are joined at the base of the hemispheres b_y commissural fibres which are bundled into structures called ‘commissures’ (the corpus callosum, the massa intermedia, and the anterior commissure are the most important of these structures). If these fibres are cut, the two hemispheres of the brain become disconnected and have no internal means of communicating with each other.