Brodmann area 46

Brain: Brodmann area 46
Latin	Area frontalis media
NeuroLex ID	birnlex_1778

Brodmann area 46, or BA46, is part of the frontal cortex in the human brain. 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 and the most rostral portion of the inferior frontal gyrus. Brodmann area 46 roughly corresponds with the dorsolateral prefrontal cortex (DLPFC), although the borders of area 46 are based on cytoarchitecture 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 and caudally by the triangular area 45 (Brodmann-1909). There is some discrepancy between the extent of BA8 (Brodmann-1905) and the same area as described by Walker (1940)^[1]

Function

The DLPFC plays a role in sustaining attention and working memory. Lesions to the DLPFC impair short-term memory and cause difficulty inhibiting responses. Lesions may also eliminate much of the ability to make judgements about what's relevant and what's not as well as causing problems in organization.

The DLPFC has recently been found to be involved in exhibiting self-control. http://sciencenow.sciencemag.org/cgi/content/full/2009/501/3 - URL Not Found

The dorsolateral prefrontal cortex is one of the few areas deactivated during REM sleep.

Research in enhancing working memory has been done by the use of transcranial direct current stimulation (tDCS) to the DLPFC. Which tDCS is believed to excite the shift in membrane potential in either a depolarization or hyperbolizing direction. So the desire effect of this method would be to strengthen synaptic transmission for long-term potentiation (LTP) during post stimulation of the DLPFC, a key to learning.

In a very brief limited research study participants tested their working memory (WM) by digit span exercises then underwent tDCS for ten minutes then perform digit span exercises from forward and backward memorization again, which showed little significance of post stimulation improvement in WM.^[2] Yet due to the lack of coherent resources and data of the experiment, more WM experiments using tDCS needs to be evaluated. Some applications being discuss is using tDCS adjunctively with cognitive remediation to enhance WM in neurologic and psychiatric conditions.

A recent study found that targeting Transcranial magnetic stimulation to Brodmann area 46 has better clinical efficacy treating depression, as its functionally is connected (negatively correlated) to Brodmann area 25.^[3]

Image

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  Animation.

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  Frontal view.

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  Lateral view.

References

• Petrides, M., Pandya, D.M., (1999) Dorsolateral prefrontal cortex: comparative cytoarchitectonic analysis in the human and the macaque brain and corticocortical connection patterns. European Journal of Neuroscience, Vol. 11, pp. 1011–1036

• Andrews S, Hoy K, Enticott P, Daskalakis Z, Fitzgerald P. Improving working memory: The effect of combining cognitive activity and anodal transcranial direct current stimulation to the left dorsolateral prefrontal cortex. Brain Stimulation [serial online]. April 2011; 4(2):84-89. Available from: PsycINFO, Ipswich, MA. Accessed February 19, 2013. http://search.ebscohost.com.leo.lib.unomaha.edu/login.aspx?direct=true&db=psyh&AN=2010-16899-001&site=ehost-live

External links

• For Neuroanatomy of the area visit BrainInfo

See also

Wikimedia Commons has media related to Brodmann area 46.

• Brodmann area
• List of regions in the human brain