APA Dictionary of Psychology

the arrangement of components in a structure, particularly the orderly spatial relationship between the distribution of neural receptors in an area of the body and a related distribution of neurons representing the same functions in cortical sensory regions of the brain. Thus, the motor cortex shows somatotopic organization, the primary visual cortex shows a topographic mapping of the retina (see retinotopic map), and the auditory system shows tonotopic organization.