Lateralisation refers to the principle that some brain functions are only represented in one hemisphere, or at least that this function is found more strongly in one hemisphere than the other.
The brain consists of two hemispheres, which are also called hemispheres (in scientific literature). Generally speaking, one hemisphere seems to be the mirror image of the other. Many brain areas are therefore found twice in the brain, such as the auditory cortex, the hippocampus, the motor cortex, and so on. Yet certain functions are more pronounced in only one hemisphere. For example, speech in most (right-handed) people is regulated in the left hemisphere. This is called lateralisation of the speech function. If a function is represented in only one hemisphere, this is also called a unilateral representation. Bilateral representation refers to the fact that a function is controlled in both the left and the right hemisphere.
Author: Job van den Hurk (translated by Thomas von Rein)