Arcuate fasciculus

Brain: Arcuate fasciculus
Diffusion tensor imaging image of the brain showing the right and left arcuate fasciculus (Raf & Laf). Also shown are the right and left superior longitudinal fasciculus (Rslf & Lslf), and tapetum of corpus callosum (Ta).
Latin	fasciculus arcuatus
NeuroNames	ancil-540

The arcuate fasciculus (Latin, curved bundle) is the neural pathway connecting the posterior part of the temporoparietal junction with the frontal cortex in the brain and is now considered as part of the superior longitudinal fasciculus.^{[citation needed]}.

Neuroanatomy

While previously thought to connect Wernicke's area and Broca's area, new research demonstrates that the arcuate fasciculus instead connects posterior receptive areas with premotor/motor areas, and not to Broca's area.

Although the regions the arcuate fasciculus connects to is still in debate, the "connectivity" of the arcuate has been shown to correspond to various functional areas within the temporal, parietal, and frontal lobes As fractional anisotropy of the arcuate increases, cortical thickness increases in corresponding areas. These findings thus suggest that particular components of white matter microstructure and regional increases in cortical thickness benefit aspects of language processing. Furthermore, the topographical relationships between independent measures of white matter and gray matter integrity suggest that rich developmental or environmental interactions influence brain structure and function where the presence and strength of such associations may elucidate pathophysiological processes influencing language systems.

The function of the arcuate fasciculus in the nondominant hemisphere is not well studied.^{[citation needed]}

Pathology

Damage to this pathway can cause a form of aphasia known as conduction aphasia, where auditory comprehension and speech articulation are preserved, but people find it difficult to repeat heard speech.

In nine of ten people with tone deafness, the superior arcuate fasciculus in the right hemisphere could not be detected, suggesting a disconnection between the posterior superior temporal gyrus and the posterior inferior frontal gyrus. Researchers suggested the posterior superior temporal gyrus was the origin of the disorder.

See also

• aphasia

External links

• http://www.lib.mcg.edu/edu/eshuphysio/program/section8/8ch15/s8c15_14.htm
• http://thebrain.mcgill.ca/flash/d/d_10/d_10_cr/d_10_cr_lan/d_10_cr_lan.html
• http://brain.oxfordjournals.org/cgi/reprint/awh622v1.pdf