Brodmann area 18

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Brodmann area 18 (BA18) is a part of the occipital cortex in the brain and makes up much of the visual part of the brain. It is known as the Visual Association Area or V2 and helps process visual information after the primary visual cortex (V1). BA18 is also called parastriate area 18.

Location and boundaries:
In humans, BA18 lies in areas of the cuneus, lingual gyrus, and the lateral occipital gyrus at the back of the brain. It is next to BA17 (which has a distinctive stripe called the Stria of Gennari) and BA19 (the peristriate area).

What it does:
BA18 is an early stage in processing visual features, helping to interpret retinotopic images that come from V1.

Structure (how it’s built):
BA18 is defined by its cell layout. It is relatively thin compared with many other brain areas. Key features include:
- a thick inner granular layer called layer IV with many small cells
- a distinct sublayer 3b just above layer IV that has closely packed large pyramidal cells
- a very narrow internal pyramidal layer V with few large cells
- a narrow, dense layer VI composed of small cells forming a boundary with the white matter

Species note:
In monkeys, BA18 is known as parastriate area 18 and is similar in structure to the human BA18.