Occipital Lobe — Visual Cortex

Anatomy

• V1 (BA 17, striate cortex): on both banks of the calcarine sulcus; the stria of Gennari.
• V2–V3 (BA 18) and association areas (BA 19); V4 (color) ventrally, V5/MT (motion) at the temporo-occipital junction.
• The cuneus (above the calcarine) represents the lower visual field, the lingual gyrus (below the calcarine) the upper visual field.
• Input from the lateral geniculate body via the optic radiation. Blood supply: PCA (calcarine artery); the occipital pole is an MCA–PCA border zone.

Functions

• Retinotopic visual map; analysis of edges, orientation, contrast and spatial frequency.
• Color (V4), motion (V5/MT), binocular depth (stereopsis).
• Feeds the dorsal (parietal — “where/how”) and ventral (temporal — “what”) streams.

Connections and chemistry

• Thalamus — lateral geniculate body and pulvinar
• Parietal cortex (dorsal stream)
• Inferior temporal/fusiform cortex (ventral stream)
• Frontal eye field
• Superior colliculus

Development

Developmental course through childhood and adolescence.

• The critical period for binocular vision and visual acuity is the first years; amblyopia needs early treatment.
• Synaptic density in V1 peaks in infancy (around 8 months) and is then pruned (Huttenlocher).
• Visual cortex is among the earliest-maturing cortical areas.

Clinical

• Cortical/cerebral visual impairment (CVI): the most common cause of childhood visual impairment in developed countries (24% in a US registry of ages 0–3; up to 48% of severe visual loss in the UK). The most common cause is hypoxic-ischemic injury, especially periventricular leukomalacia in preterm infants. The eye examination can be normal; it may be mistaken for a behavior or learning problem. A
• ASD: detail-focused (local) visual processing.
• Childhood occipital epilepsies: Panayiotopoulos syndrome (autonomic), Gastaut type (visual hallucinations).
• Migraine aura (cortical spreading depression).

Treatment

This region from the perspective of medication, psychotherapy and neuromodulation. Letter badges are evidence levels.

• Preventive drugs for childhood migraine: in the CHAMP trial (ages 8–17, 361 patients) amitriptyline and topiramate were not superior to placebo (at least 50% reduction in attack frequency: 52%, 55%, placebo 61%) and had more side effects (Powers et al., 2017). Lifestyle measures and CBT are the basis of prevention. A
• In CVI: adapting the visual environment (high contrast, plain background, moving and colorful objects) and early visual rehabilitation. C
• Most occipital epilepsies (e.g. Panayiotopoulos syndrome) are benign; antiepileptic drugs for frequent seizures.

Assessment

Neuropsychological tasks and measures that probe this region's function.

• Visual field examination (confrontation, perimetry)
• Visual perception tests (Beery VMI visual perception subtest)
• Visual evoked potentials (VEP), motion perception thresholds

Lesions and damage

Clinical findings expected with damage or dysfunction.

• Contralateral homonymous hemianopia (the macula may be spared).
• Bilateral: cortical blindness, Anton syndrome (denial of blindness).
• Akinetopsia (V5), achromatopsia (V4), visual hallucinations and illusions.

In the model

How this structure is defined in the 3D model, and the data source.

Lateral occipital cortex, cuneus, lingual gyrus and pericalcarine cortex.

References

Full citations for the card; links go to the paper (DOI) or a PubMed search.

1. Powers SW et al. Trial of amitriptyline, topiramate, and placebo for pediatric migraine. N Engl J Med 2017;376(2):115–124. Search PubMed
2. CVI epidemiyolojisi: ABD ulusal kayıt (2.155 çocuk, 0–3 yaş) and NEI özetleri. Search PubMed