Lingual gyrus

The lingual gyrus is a tongue-shaped structure that lies on the medial aspect of the occipital lobe along the tentorialinferomedial (tentorial) surface ¹. It sits inferior to

Relations

Superiorly lies the cuneus (separated from the lingual gyrus by the calcarine sulcus) and superior to.

Inferolaterally lies the fusiform gyrus (separated from it by the collateral sulcus). It

Anteriorly the lingual gyrus is continuous with the parahippocampal gyrus, together sometimes referred to as the medial occipitotemporal gyrus ¹². 

Posterology it is continuous with occipital pole and the inferior occipital gyrus which runs along the lateralinferolateral surface of the occipital lobe ².

Blood supply

The lingual gyrus is supplied largely by the calcarine artery, but can also receive blood from the lingual gyrus artery, posterior temporal artery and common temporal artery in a proportion of people (8.3%, 60% and 28.4% respectively in one study) ³.

Function 

A variety of visual functions have been attributed to the lingual gyrus, and a degree of lateralisation of function appears to exist with respect to this:.

Right lingual gyrus

The right lingual gyrus appears to be involved in the perception and recognition of familiar landmarks and scenes as well as the identification of faces. Topographical recognition seems to reside in the anterior half while recognition of faces is located mainly in the posterior half.

The right lingual gyrus (and possibly the left) may also play a role in dreaming.

Bilateral lingual gyri

fMRI studies have found that visual identification of facial expressions of emotions involved bilateral activation of the lingual gyrus, among other brain regions ⁴.

Fibres of the inferior optic radiation corresponding to the upper quadrant of the contralateral visual field synapse on the lingual gyrus ⁵.

Related pathology

Right lingual gyrus

Following from its functions lesions to the right lingual gyrus produce topographagnosia (an inability to recognise landmarks) and prosopagnosia (an inability to recognise faces) ^6,7.

In relation to its function in dreaming, one case report describes the total loss of dreams in a patient who suffered bilateral deep occipital lobe infarcts (including the right inferior lingual gyrus) in the absence of any other neuropsychological deficits. This condition has previously been described in the literature and is known as Charcot-Wilbrand syndrome, and is usually associated with prosopagnosia, topographagnosia and visual irreminiscence (an inability to recall visual images in dreams during wakefulness) ⁸.

Hypermetabolism in the right lingual gyrus has also been correlated to a condition called 'visual snow', a visual disturbance of positive phenomena where small flickering dots occur throughout the entire visual field and is said to resemble the static of a poorly tuned analog television ⁹.

Bilateral lingual gyri

The lingual gyrus on both sides also seem to play a role in the perception of visual space as lesions on either side result in the clinical phenomenon known as line bisection error (LBE), in which patients wrongly bisect a horizontal line ^10,11.

As a consequence of the input from the inferior optic radiation, lesions would result in a contralateral superior quadrantanopia ^5.