Primary visual cortex

The primary visual cortex, or V1, is the first cortical region to process visual signals relayed from the eyes. It lies in the occipital lobe and analyzes features such as edges, orientation, and spatial position.

Lateral geniculate nucleus: A visual relay nucleus in the thalamus that sends retinal signals to the cerebral cortex. Most visual information reaches V1 through this thalamic relay.
Retina: The light-sensitive tissue lining the back of the eye, where photoreceptors begin visual signaling. V1's input ultimately originates in the retinal circuits that encode light.
V1 lesion: Damage to primary visual cortex that can cause loss of conscious vision in corresponding parts of the visual field. Lesions established that intact V1 is central to ordinary conscious visual perception.
Extrastriate cortex: Visual cortical regions outside V1 that perform further processing of visual information. These areas build on V1 signals to represent more complex visual properties.
Retinotopy: The preservation of spatial relationships between locations in the visual field and locations in the brain. V1 arranges nearby visual-field locations in nearby cortical regions.
Retinal ganglion cell: A retina neuron whose axons carry visual signals toward the brain through the optic nerve. Ganglion-cell axons form the incoming signal pathway that eventually reaches V1.
Blindsight: The ability to respond to visual stimuli without conscious visual awareness, often after damage to V1. Some visual abilities can persist without normal conscious vision after V1 injury.
Dorsal stream: A visual processing pathway associated with spatial relations, motion, and visually guided action. It carries information from early visual areas toward parietal regions for spatial processing.
Orientation selectivity: The preferential response of a neuron to edges or bars at a particular angle. Many V1 neurons respond most strongly to contours with a specific orientation.
Optic chiasm: The junction where some optic-nerve fibers cross to the opposite side of the brain. Its partial crossing helps route each visual hemifield to the opposite hemisphere's V1.

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