Human

Brodmann area 18, or BA18, is part of the

occipital The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...

cortex in the

human brain The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the ...

. It accounts for the bulk of the volume of the occipital lobe. It is known as a "Visual Association Area" or V2 and is a first stage in processing or

feature extraction In machine learning, pattern recognition, and image processing, feature extraction starts from an initial set of measured data and builds derived values (features) intended to be informative and non-redundant, facilitating the subsequent learning a ...

retinotopic Retinotopy (from Greek τόπος, place) is the mapping of visual input from the retina to neurons, particularly those neurons within the visual stream. For clarity, 'retinotopy' can be replaced with 'retinal mapping', and 'retinotopic' with 'r ...

images from V1. This area is also known as parastriate area 18. It is a subdivision of the cytoarchitecturally defined occipital region of

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...

. In the human it is located in parts of the

cuneus The cuneus (; plural cunei) is a smaller lobe in the occipital lobe of the brain. The cuneus is bounded anteriorly by the parieto-occipital sulcus and inferiorly by the calcarine sulcus. Function The cuneus (Brodmann area 17) receives visua ...

, the

lingual gyrus The lingual gyrus, also known as the ''medial'' occipitotemporal gyrus, is a brain structure that is linked to processing vision, especially related to letters. It is thought to also play a role in analysis of logical conditions (i.e., logical ord ...

and the lateral occipital gyrus (H) of the

occipital lobe The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head". The occipital lobe is the vi ...

. It is bounded on one side by the

Brodmann area 17 The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and ...

, from which it is distinguished by absence of a band of Gennari, and on the other by the peristriate area 19 (Brodmann-1909).

Guenon

Brodmann area 18 is a subdivision of the cerebral cortex of the

guenon The guenons (, ) are Old World monkeys of the genus ''Cercopithecus'' (). Not all members of this genus have the word "guenon" in their common names; also, because of changes in scientific classification, some monkeys in other genera may have co ...

defined on the basis of cytoarchitecture. It is topographically and cytoarchitecturally homologous to parastriate area 18 of the human (Brodmann-1909). Distinctive features (Brodmann-1905): a wide, dense internal

granular cell Juxtaglomerular cells (JG cells), also known as juxtaglomerular granular cells are cells in the kidney that synthesize, store, and secrete the enzyme renin. They are specialized smooth muscle cells mainly in the walls of the afferent arteriole ...

layer (IV); a distinct sublayer 3b of closely packed large

pyramidal cell Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cor ...

s positioned in the external

pyramidal layer A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilater ...

(III) directly above layer IV; an almost cell-free, narrow internal pyramidal layer (V) with no larger

ganglion cells {{stack, A ganglion cell is a cell found in a ganglion. Examples of ganglion cells include: * Retinal ganglion cell (RGC) found in the ganglion cell layer of the retina * Cells that reside in the adrenal medulla, where they are involved in the s ...

; a very narrow, dense

multiform layer The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...

(VI) composed of small

polymorphic cell Polymorphism, polymorphic, polymorph, polymorphous, or polymorphy may refer to: Computing * Polymorphism (computer science), the ability in programming to present the same programming interface for differing underlying forms * Ad hoc polymorphism ...

s that form a distinct boundary with the underlying subcortical

white matter White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribution ...

. Like

area 17 of Brodmann The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and ...

-1905, area 18 is relatively thin, with the three deep layers thin relative to the three outer layers, and has distinct boundaries between layers, abundance of

granule cell A granule is a large particle or grain. It can refer to: * Granule (cell biology), any of several submicroscopic structures, some with explicable origins, others noted only as cell type-specific features of unknown function ** Azurophilic granul ...

s, narrow layer VI, and sharp boundary between cortex and subcortical white matter.

External links

* For Neuroanatomy of the parastriate area 18 visi
BrainInfo
* For Neuroanatomy of Brodmann area 18 visi
BrainInfo
{{Prosencephalon 18 Occipital lobe

Human

Guenon

See also

External links