Lateral occipitotemporal gyrus

At a glance

English

Lateral occipitotemporal gyrus

Latin (TA2)

Gyrus occipitotemporalis lateralis

System

Brain and spinal cord

Region

Head

Side

Paired, left and right

About the lateral occipitotemporal gyrus

The lateral occipitotemporal gyrus is better known as the fusiform gyrus, from the Latin for spindle-shaped, because it is broad in the middle and narrows at each end. The German anatomist Emil Huschke gave it that name in the nineteenth century. It lies on the basal (inferior) surface of the hemisphere, stretching from the temporal lobe back into the occipital lobe, and it is the largest structure of the ventral temporal cortex. Much of it corresponds to Brodmann area 37.

It is bounded on its lateral side by the occipitotemporal sulcus, which separates it from the inferior temporal gyrus, and on its medial side by the collateral sulcus, which separates it from the parahippocampal gyrus in front and the lingual gyrus behind (together the medial occipitotemporal gyrus). A shallow groove along its length, the mid-fusiform sulcus, splits it into lateral and medial strips. The fusiform gyrus as a distinct structure is found in humans and great apes but not in macaque monkeys.

The gyrus belongs to the ventral visual stream, which identifies what an object is. Its lateral strip, especially on the right and next to the mid-fusiform sulcus, contains the fusiform face area, which responds strongly to faces; neighbouring patches respond to bodies. On the left, a region in and near the occipitotemporal sulcus becomes tuned to written words as a person learns to read and is often called the visual word form area. Other parts take part in colour processing and in fine distinctions within a category, such as telling one bird or car model from another. The left side seems to detect face-like features while the right decides whether a face is really present. Its activity during face tasks is linked with dopamine signalling.

Damage to the fusiform gyrus, usually from a posterior cerebral artery stroke, can cause prosopagnosia, an inability to recognise familiar faces, especially when the right side is affected, and pure alexia, loss of reading with preserved writing, when the left side is affected. Loss of colour vision (cerebral achromatopsia) may accompany it. Reduced activity or grey matter in the region has been reported in dyslexia and, in autism, lower responses to faces. Overactivity here is linked with hallucinations of faces, and with the colour experiences of grapheme-colour synaesthesia.

Function and supply

Function

Part of the ventral visual stream: recognises faces, bodies, written words and colours, and makes fine distinctions within a category.

Blood supply

Inferior temporal branches of the posterior cerebral artery.