Sensory and Visual System Anatomy and Physiology Practice Test

The spatial map from the retina is preserved as it travels to cortex primarily by the thalamus, specifically the lateral geniculate nucleus (LGN). Retinal ganglion cells project to the LGN in a way that preserves retinotopy—nearby points on the retina connect to nearby LGN neurons, maintaining the same spatial layout. From the LGN, these signals are relayed to the primary visual cortex via the optic radiations, carrying that preserved map into cortical space. Brainstem reflex circuits don’t maintain this detailed spatial organization, and while the visual cortex also contains retinotopic maps, the key relay that preserves the layout on the way to cortex is the thalamic LGN.