Brodmann area 8 is one of Brodmann's

cytological Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and ...

ly defined regions of the brain. It is involved in planning complex movements.

Human

Brodmann area 8, or BA8, is part of the

frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music * The Front (band), an American rock band signed to Columbia Records and active in the 1980s and e ...

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

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 ...

. Situated just anterior to the premotor cortex ( BA6), it includes the

frontal eye fields The frontal eye fields (FEF) are a region located in the frontal cortex, more specifically in Brodmann area 8 or BA8, of the primate brain. In humans, it can be more accurately said to lie in a region around the intersection of the middle fronta ...

(so-named because they are believed to play an important role in the control of eye movements). Damage to this area, by stroke, trauma or infection, causes tonic deviation of the eyes towards the side of the injury. This finding occurs during the first few hours of an acute event such as cerebrovascular infarct (stroke) or hemorrhage (bleeding).

Guenon

The term Brodmann area 8 refers to a cytoarchitecturally defined portion of the frontal lobe 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 ...

. Located rostral to the

arcuate sulcus ''Arcuate'' (Latin for "curved") can refer to: Anatomy * Arcuate fasciculus * Arcuate line (disambiguation) * Arcuate artery (disambiguation), several arteries * Arcuate nucleus * Arcuate nucleus (medulla) * Arcuate ligaments of the diaphragm * A ...

, it was not considered by Brodmann-1909 to be topographically homologous to the intermediate frontal area 8 of the human. Distinctive features (Brodmann-1905): compared to

Brodmann area 6 Brodmann area 6 (BA6) is part of the frontal cortex in the human brain. Situated just anterior to the primary motor cortex ( BA4), it is composed of the premotor cortex and, medially, the supplementary motor area (SMA). This large area of the fron ...

-1909, area 8 has a diffuse but clearly present internal granular layer (IV); sublayer 3b of 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) has densely distributed medium-sized pyramidal cells; the internal pyramidal layer (V) has 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 th ...

densely distributed with some

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 interspersed; the external granular layer (II) is denser and broader; cell layers are more distinct; the abundance of cells is somewhat greater.

Functions

The area is involved in the management of uncertainty. A

functional magnetic resonance imaging Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area o ...

study demonstrated that Brodmann area 8 activation occurs when test subjects experience uncertainty, and that with increasing uncertainty there is increasing activation. An alternative interpretation is that this activation in frontal cortex encodes hope, a higher-order expectation positively correlated with uncertainty.Chew and Ho,
Hope: An Empirical Study of Attitude toward the Timing of Uncertainty Resolution
', J Risk and Uncertainty 8(3):267-288. 1994

Image

File:Brodmann area 8 animation small.gif, Animation. File:Brodmann area 8 frontal.jpg, front view. File:Brodmann area 8 lateral.jpg, Lateral view. File:Brodmann area 8 medial.jpg, Medial view.

References

{{Prosencephalon 08 Frontal lobe

Human

Guenon

Functions

Image

See also

References