Occipitallohkon

Occipitallohkon, or the occipital lobe, is the rearmost region of the cerebral cortex. It is primarily devoted to processing visual information and sits at the back of the brain. Its borders are defined by landmarks such as the parieto-occipital sulcus and the calcarine sulcus, with the primary visual cortex located along the banks of the calcarine fissure. The primary visual cortex, or V1 (Brodmann area 17), lies near the midline in both hemispheres, with surrounding secondary and higher-order areas (V2, V3, V4, and V5/MT) contributing to color, form, depth, and motion perception.

Afferent visual input to the occipitallohkon travels from the retina through the lateral geniculate nucleus of the thalamus to V1, preserving a retinotopic map. From there, information is processed along two major pathways: the dorsal stream, projecting to the parietal lobes, supports spatial localization and action guidance; and the ventral stream, projecting to the temporal lobes, supports object recognition and color processing. These pathways integrate with other sensory and cognitive systems to support perception and behavior.

Clinical significance: lesions within the occipitallohkon can produce visual field defects such as contralateral homonymous hemianopia, or more focal deficits depending on the damaged region. V1 injury can cause cortical blindness, while damage to ventral stream areas may lead to visual agnosias or prosopagnosia. Damage to V4 can cause achromatopsia, and lesions to MT/V5 can impair motion perception. Developmentally, the occipitallohkon exhibits experience-dependent plasticity, particularly in early life, with potential for partial recovery after injury.