It interconnects multiple cortical regions of the temporal lobes, the amygdalae, and olfactory bulbs.^[1] It is a part of the neospinothalamic tract for pain.^{[citation needed]}

The functionality of the anterior commissure is still not completely understood. Researchers have implicated it in functions ranging from colour perception to attention. One such study supported colour perception in callosal agenesis (Those born without a corpus callosum; Barr & Corballis, 2002).^[3] Other studies have built on this to imply that the anterior commissure can be a compensatory pathway in those without a corpus callosum, presenting diffusion tensor imaging (DTI) techniques to better elucidate the anterior commissure and how it might be implicated in various functions (Winter & Franz, 2014).^[2]

Sexuality edit

In 1992, Laura Allen and Roger Gorski of UCLA measured the anterior commissures of 30 homosexual men, 30 heterosexual men, and 30 heterosexual women. They found that all three groups' commissures were significantly different from one another, with homosexual males having the largest anterior commissure, followed by heterosexual women, and then heterosexual men, who had the smallest anterior commissures.^[4]

In 1993, a review by Byne and Parsons criticized this research, noting that 27 of the 33 homosexual males fell within the range of heterosexual males in the study.^[5] However, because range is defined only by the two most extreme data points in a group,^[6] the existence of a single heterosexual male with an exceptionally large anterior commissure for his group (an outlier^[7]) would cause this large range irrespective of the data from the rest of the individuals in the group. This individual's existence would not change the fact that the groups on average were quite different from one another, and that these differences were statistically significant.^[4]

A later report by Byne et al. (2001) noted that

We also measured the anterior commissure in the same blocks of tissue used for the present hypothalamic study (data not shown) and were unable to replicate a report (by Allen and Gorski) that its cross-sectional area is larger in women than in men.^[8]

Also, a study by Lasco et al. (2002) said:

We examined the cross-sectional area of the AC in postmortem material from 120 individuals, and found no variation in the size of the AC with age, HIV status, sex, or sexual orientation.^[9]

The corpus callosum allows for communication between the two hemispheres and is found only in placental mammals (the eutherians), while it is absent in monotremes and marsupials, as well as other vertebrates such as birds, reptiles, amphibians and fish. The anterior commissure serves as the primary mode of interhemispheric communication in marsupials,^[10][11] and which carries all the commissural fibers arising from the neocortex (also known as the neopallium), whereas in placental mammals the anterior commissure carries only some of these fibers).^[12]

•  
  Anterior commissure

• Posterior commissure
• Corpus callosum

  This article incorporates text in the public domain from page 840 of the 20th edition of Gray's Anatomy (1918)

• Overview Archived 2006-01-11 at the Wayback Machine at University of Cambridge
• "Anatomy diagram: 13048.000-3". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2012-07-22.
• https://web.archive.org/web/20070512234725/http://www2.umdnj.edu/~neuro/studyaid/Practical2000/Q09.htm
• Allen LS, Gorski RA (August 1992). "Sexual orientation and the size of the anterior commissure in the human brain". Proc. Natl. Acad. Sci. U.S.A. 89 (15): 7199–202. Bibcode:1992PNAS...89.7199A. doi:10.1073/pnas.89.15.7199. PMC 49673. PMID 1496013.
• NIF Search - Anterior Commissure via the Neuroscience Information Framework