Noun | 1. | ![]() optic radiation, radiatio optica - a nerve pathway from the lateral geniculate body to the visual cortex commissure - a bundle of nerve fibers passing from one side to the other of the brain or spinal cord cerebral peduncle, peduncle - a bundle of myelinated neurons joining different parts of the brain substantia alba, white matter - whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths |