Brodmann area 9
Encyclopedia
Human
Brodmann area 9, or BA9, is part of the frontalFrontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
in the human brain
Human brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
. It contributes to the dorsolateral prefrontal cortex
Dorsolateral prefrontal cortex
The dorsolateral prefrontal cortex , according to a more restricted definition, is roughly equivalent to Brodmann areas 9 and 46. According to a broader definition DL-PFC consists of the lateral portions of Brodmann areas 9 – 12, of areas 45, 46, and the superior part of area 47. These regions...
.
Guenon
The term Brodmann area 9 refers to a cytoarchitecturally defined portion of the frontal lobe of the guenonGuenon
The guenons are the genus Cercopithecus of Old World monkeys. Not all the members of this genus have the word "guenon" in their common names, and because of changes in scientific classification, some monkeys in other genera may have common names that do include the word "guenon"...
. Brodmann-1909 regarded it on the whole as topographically and cytoarchitecturally homologous
Homology (biology)
Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...
to the granular frontal area 9 and frontopolar area 10 in the human. Distinctive features (Brodmann-1905): unlike Brodmann area 6
Brodmann area 6
- Human :Brodmann area 6 is part of the frontal cortex in the human brain. Situated just anterior to the primary motor cortex , it is composed of the premotor cortex and, medially, the supplementary motor area, or SMA...
-1909, area 9 has a distinct internal granular layer (IV); unlike Brodmann area 6
Brodmann area 6
- Human :Brodmann area 6 is part of the frontal cortex in the human brain. Situated just anterior to the primary motor cortex , it is composed of the premotor cortex and, medially, the supplementary motor area, or SMA...
or Brodmann area 8
Brodmann area 8
Brodmann area 8 is one of Brodmann's cytologically defined regions of the brain. It is involved in planning complex movements.-Human:Brodmann area 8, or BA8, is part of the frontal cortex in the human brain...
-1909 its internal pyramdal layer (V) is divisible into two sublayers, an outer layer 5a of densely distributed medium sized ganglion cell
Ganglion cell
A retinal ganglion cell is a type of neuron located near the inner surface of the retina of the eye. It receives visual information from photoreceptors via two intermediate neuron types: bipolar cells and amacrine cells...
s that partially merges with layer IV, and an inner, clearer, cell-poor layer 5b; the pyramidal cell
Pyramidal cell
Pyramidal neurons are a type of neuron found in areas of the brain including cerebral cortex, the hippocampus, and in the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract. Pyramidal neurons were first discovered and...
s of sublayer 3b of the external pyramidal layer (III) are smaller and sparser in distribution; the external granular layer
Granular layer
The term granular layer may refer to:*the granular layer of Tomes, seen in dentin of the teeth. When dry section of the root dentin of teeth are visualized under transmitted light, a granular layer is seen adjacent to cementum.It is believed to be caused by coalescing & looping of terminal portion...
(II) is narrow, with small numbers of sparsely distributed granule cell
Granule cell
In neuroscience, granule cells refer to tiny neurons that are around 10 micrometres in diameter. Granule cells are found within the granular layer of the cerebellum , the dentate gyrus of the...
s.
External links
- For Neuroanatomy of this area see BrainInfo
It is the medial prefrontal cortex.
See also
- Brodmann areaBrodmann areaA Brodmann area is a region of the cerebral cortex defined based on its cytoarchitectonics, or structure and organization of cells.-History:...
- List of regions in the human brain
- http://www.pnas.org/cgi/reprint/98/7/4259.pdf