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Brodmann area 46, or BA46, 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 ea ...
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 ...
. It is between BA10 and BA45. BA46 is known as middle frontal area 46. In the human brain it occupies approximately the middle third of the
middle frontal gyrus The middle frontal gyrus makes up about one-third of the frontal lobe of the human brain. (A ''gyrus'' is one of the prominent "bumps" or "ridges" on the surface of the human brain.) The middle frontal gyrus, like the inferior frontal gyrus an ...
and the most rostral portion of the
inferior frontal gyrus The inferior frontal gyrus (IFG), (gyrus frontalis inferior), is the lowest positioned gyrus of the frontal gyri, of the frontal lobe, and is part of the prefrontal cortex. Its superior border is the inferior frontal sulcus (which divides it f ...
. Brodmann area 46 roughly corresponds with the
dorsolateral prefrontal cortex The dorsolateral prefrontal cortex (DLPFC or DL-PFC) is an area in the prefrontal cortex of the primate brain. It is one of the most recently derived parts of the human brain. It undergoes a prolonged period of maturation which lasts until adult ...
(DLPFC), although the borders of area 46 are based on
cytoarchitecture Cytoarchitecture ( Greek '' κύτος''= "cell" + '' ἀρχιτεκτονική''= "architecture"), also known as cytoarchitectonics, is the study of the cellular composition of the central nervous system's tissues under the microscope. Cytoarc ...
rather than function. The DLPFC also encompasses part of granular frontal area 9, directly adjacent on the dorsal surface of the cortex. Cytoarchitecturally, BA46 is bounded dorsally by the granular frontal area 9, rostroventrally by the
frontopolar area 10 Brodmann area 10 (BA10, frontopolar prefrontal cortex, rostrolateral prefrontal cortex, or anterior prefrontal cortex) is the anterior-most portion of the prefrontal cortex in the human brain. BA10 was originally defined broadly in terms of its c ...
and caudally by the
triangular area 45 Brodmann area 45 (BA45), is part of the frontal cortex in the human brain. It is situated on the lateral surface, inferior to BA9 and adjacent to BA46. This area in humans occupies the triangular part of inferior frontal gyrus (H) and, surroun ...
(Brodmann-1909). There is some discrepancy between the extent of BA8 (Brodmann-1905) and the same area as described by
Walker Walker or The Walker may refer to: People * Walker (given name) *Walker (surname) * Walker (Brazilian footballer) (born 1982), Brazilian footballer Places In the United States *Walker, Arizona, in Yavapai County *Walker, Mono County, California ...
(1940).


Function

The dorsolateral prefrontal cortex plays a central role in sustaining
attention Attention is the behavioral and cognitive process of selectively concentrating on a discrete aspect of information, whether considered subjective or objective, while ignoring other perceivable information. William James (1890) wrote that "Att ...
and managing
working memory Working memory is a cognitive system with a limited capacity that can hold information temporarily. It is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-term memory, ...
, and has recently been shown to regulate self-control. It is one of the few cortical areas whose activity diminishes during REM sleep. The high connectivity of this area within the frontal lobe as well as other parts of the brain means that damage can have a wide variety of effects. Lesions impair short-term memory, cause difficulty inhibiting responses, impair the ability to judge the relevance of stimuli, and cause problems in organization. Recent research has shed light on the mechanism of working memory and the role of the dorsolateral prefrontal cortex. Studies using transcranial direct current stimulation (tDCS) observe changes in cortical activity due to either depolarization or hyperpolarization of underlying areas. The effect of these voltage shifts on activity in other structures is then measured. The goal of the studies is to identify the role of the dorsolateral prefrontal cortex in memory circuit modulation and learning. In a limited research study, participants tested their baseline working memory with digit span exercises, then underwent tDCS for ten minutes before being retested with the exercises. Contrary to expectations, tDCS showed only minimal effects on working memory. Due to the lack of coherent resources and data of the experiment, more WM experiments using tDCS need to be evaluated. Some applications being discussed involve using tDCS adjunctively with cognitive remediation to enhance WM in neurologic and psychiatric conditions. A recent study found that targeting
Transcranial magnetic stimulation Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing magnetic field is used to induce an electric current at a specific area of the brain through electromagnetic induction. An electric pulse gener ...
to Brodmann area 46 has better clinical efficacy treating depression, as its functionally is connected (negatively correlated) to
Brodmann area 25 Brodmann area 25 (BA25) is the subgenual area, area subgenualis or subgenual cingulatea area in the cerebral cortex of the brain and delineated based on its cytoarchitectonic characteristics. It is the 25th " Brodmann area" defined by Korbinian ...
.


Image

File:Brodmann area 46 animation small.gif, Animation. File:Brodmann area 46 frontal.jpg, Frontal view. File:Brodmann area 46 lateral.jpg, Lateral view.


See also

*
Brodmann area A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells. History Brodmann areas were originally defined and numbered by th ...
*
List of regions in the human brain The human brain anatomical regions are ordered following standard neuroanatomy hierarchies. Functional, connective, and developmental regions are listed in parentheses where appropriate. Hindbrain (rhombencephalon) Myelencephalon *M ...


References


Sources

* *


External links

* For Neuroanatomy of the area visi
BrainInfo
{{DEFAULTSORT:Brodmann Area 46 46 Frontal lobe