Brodmann 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 cytoarchitectonic traits as they were observed in the brains of cadavers, but because modern functional imaging cannot precisely identify these boundaries, the terms anterior prefrontal cortex, rostral prefrontal cortex and frontopolar prefrontal cortex are used to refer to the area in the most anterior part of the frontal cortex that approximately covers BA10—simply to emphasize the fact that BA10 does not include all parts of the prefrontal cortex.

BA10 is the largest cytoarchitectonic area in the human brain. It has been described as "one of the least well understood regions of the human brain".

Anatomy

Size

The volume of the human BA10 is about 14 cm<sup>3</sup> and constitutes roughly 1.2% of total brain volume. This is twice what would be expected in a hominoid with a human-sized brain. By comparison, the volume of BA10 in bonobos is about 2.8 cm<sup>3</sup>, and makes up only 0.74% of its brain volume. In each hemisphere, area 10 contains an estimated 250 million neurons.

Area 10 lies underneath the air filled frontal sinus of the skull, which has limited electrophysiology research until 2009.

Relation to frontal pole

In humans the frontal pole area of the prefrontal cortex includes not only area 10 but part of BA 9. BA 10 also extends beyond the pole area into its ventromedial side. In Guenon monkeys, the pole area is filled by BA 12 (and its BA 10 is found in the orbital prefrontal region). This situation has been suggested to enable integration of inputs from multiple areas.

Subareas

BA 10 is divided into three sub-areas, 10p, 10m and 10r. 10p

occupies the frontal pole while the other two cover the ventromedial part of the prefrontal cortex. Medial frontopolar (Area 10m) cortex also contains fewer parvalbumin- and calbindin-immunoreactive neurons relative to other frontal lobe regions, especially Area 14 in orbitofrontal cortex and Area 46 in PFC.

Connections

Research upon primates suggests that area 10 has inputs and output connections with other higher-order association cortex areas particularly in the prefrontal cortex while having few with primary sensory or motor areas. Its connections through the extreme capsule link it to the auditory and multisensory areas of the superior temporal sulcus. They also continue in the medial longitudinal fasciculus in the white matter of the superior temporal gyrus areas on the superior temporal gyrus (areas TAa, TS2, and TS3) and nearby multisensory areas on the upper bank of the superior temporal sulcus (TPO). Another area connected through the extreme capsule is the ventral region of the insula. Connections through the cingulate fasciculus link area 10 to the anterior, posterior cingulate cortex, and retrosplenial cortex. The uncinate fasciculus connects it with the amygdala, temporopolar proisocortex and anterior most part of the superior temporal gyrus. There are no connections to the parietal cortex, occipital cortex nor inferotemporal cortex

Its connections have been summarized as "it seems not to be interconnected with ‘downstream’ areas in the way that other prefrontal areas are. .. it is the only prefrontal region that is predominantly (and possibly exclusively) interconnected with supramodal cortex in the PFC, anterior temporal cortex and cingulate cortex."

Function

Although this region is extensive in humans, its function is poorly understood. Cognitive branching enables a previously running task to be maintained in a pending state for subsequent retrieval and execution upon completion of the ongoing one. Many of our complex behaviors and mental activities require simultaneous engagement of multiple tasks, and they suggest the anterior prefrontal cortex may perform a domain-general function in these scheduling operations. Thus, the frontopolar cortex shares features with the central executive in Baddeley's model of working memory. However, other hypotheses have also been proffered, such as those by Burgess et al.. These also take into consideration the influence of the limbic system, to which the frontopolar cortex is connected through the ventromedial prefrontal cortex. A 2006 meta-analysis found that the rostral prefrontal cortex was involved in working memory, episodic memory and multiple-task coordination.

This area has also been implicated in decision making prior to the decision being available to conscious awareness

Images

File:Brodmann area 10 animation small.gif|Animation.

File:Brodmann area 10 frontal.jpg|front view.

File:Brodmann area 10 lateral.jpg|Lateral view.

File:Brodmann area 10 medial.jpg|Medial view.

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