fasciculus is the main connection between these two regions. Studies that challenge the claim that the arcuate fasciculus is responsible for repetition cite that in some cases lesions to the arcuate fasciculus nor total agenesis produce conduction aphasia. Progressive aphasia Progressive aphasia is a type of aphasia that slowly worsens over time. It can affect both the production and comprehension of language. Progressive aphasic patients that have lesions in their arcuate fasciculus were especially deficient in their syntax processing abilities. Worsened syntax processing correlated with the degree of degradation in the arcuate fasciculus. Tone deafness In nine out 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. Stuttering In stutterers, the arcuate fasciculus appears to have bilateral deficits that reduce it by one-third or more relative to non-stutterers. However, there is ongoing debate concerning the contribution of each hemisphere. Diffusion-based evidence of differences between stutterers and controls is not isolated to the arcuate fasciculus. Specific Language Impairment Specific language impairment is a disorder that prevents children from developing language normally. These children particularly have difficulty with the syntactic and hierarchal structures of language. Damage to the arcuate fasciculus is implicated as a possible cause of specific language impairment, however further data is required to validate this claim. Dyslexia Dyslexia is a disorder that is primarily characterized by reading deficits. Research has shown that decreases in the integrity of the arcuate fasciculus coincide with worsened reading ability in dyslexic subjects. See also Aphasia Wernicke–Geschwind model References External links https://web.archive.org/web/20070528184714/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 Cerebral white matter Central nervous system pathways