APA Dictionary of Psychology

n. a structure that forms a bridge or junction between two anatomical areas, particularly the two cerebral hemispheres or the halves of the spinal cord. Examples include the two key landmarks in brain mapping: the anterior commissure, a bundle of myelinated fibers that joins the temporal lobes and contains fibers of the olfactory tract; and the posterior commissure, a bundle of myelinated fibers that connects regions in the midbrain and diencephalon. See also corpus callosum; gray commissure; white commissure. —commissural adj.