The contralateral organization of the forebrain (Latin: contra‚ against; latus‚ side; lateral‚ sided) is the property that the hemispheres of the cerebrum and the thalamus represent mainly the contralateral side of the body. Consequently, the left side of the forebrain mostly represents the right side of the body, and the right side of the brain primarily represents the left side of the body. The contralateral organization involves both executive and sensory functions (e.g., a left-sided brain lesion may cause a right-sided hemiplegia). The contralateral organization is only present in vertebrates.
A number of theories have been put forward to explain this phenomenon, but none are generally accepted.[1] These include, among others, Cajal's visual map theory, different topological approaches, the somatic twist theory and the axial twist theory.[1]