[Abstract Title]. - Society for Neuroscience

Topic: C.05.d. ADHD, SLI, dyslexia and other specific disorders of neurobehavior
Support: NICHD (P50 HD40095)
Title: The anatomical profile of dyslexic females: a voxel-based morphometry study
Authors: *T. M. GERNER 1 , A. E. WALL 1 , E. M. NAPOLIELLO 1 , L. D. FLOWERS 1,2 , G. F.
EDEN 1 ;
1 Ctr. for the Study of Learning, Georgetown Univ., Washington, DC; 2 Wake Forest Univ.,
Winston-Salem, NC
Abstract: Developmental dyslexia is a neurologically-based specific learning disorder affecting
7-12% of the population. It is characterized by reading deficits unrelated to intellectual ability or
access to instruction and is more prevalent in males (Rutter et al., 2004). Structural imaging
studies have revealed regions of reduced grey matter volume in dyslexia (Eckert 2004). These
investigations have been limited to groups of purely male participants or groups consisting of
both males and females. The former have revealed left lateralized differences and the latter
(mixed groups) have shown bilateral temporal lobe differences in dyslexia. However, anatomical
differences have not yet been examined in purely female dyslexic samples, although it is known
that the functional anatomy of language in women is different from that found in men (Shaywitz
1995), suggesting that the brain-basis for a language learning disability in women might have a
unique neuroanatomical manifestation.
Using Voxel-Based Morphometry (Ashburner & Friston, 2000) we compared 8 adult dyslexic
females (age = 24.8 years, SD = 1.4) and 8 adult typically-reading females (age = 22.1 years, SD
= 2.6). We found decreased grey matter density in right superior parietal lobe and right inferior
temporal gyrus in addition to the previously described differences in left inferior frontal gyrus
and left superior parietal lobe. To determine whether these right hemisphere differences are also
present in children, we compared 9 female children with dyslexia (age = 9.5 years, SD = 1.3) and
8 typically-reading females (age = 10.1 years, SD = 3.0) employing the same analysis as that
used in the adults. Large areas of reduced grey matter density were found in the dyslexic group
in the inferior frontal gyrus, bilaterally. Also, we observed differences in left inferior and middle
temporal gyrus and cerebellum, as well as right hemisphere cingulate gyrus, insula and inferior
temporal gyrus.
Together these results demonstrate that reduced grey matter density is observed in females with
dyslexia in the left inferior frontal and right inferior temporal gyri as children and adults.
However, an adult-specific morphometric difference in bilateral parietal grey matter density
suggests an age-dependant anatomical difference in females with dyslexia. This age-dependant
change in parietal cortices could be induced developmentally or as a consequence of
compensatory mechanisms associated with difficulties in reading acquisition. We conclude that
the brain basis for dyslexia varies as a function of gender and age.
Disclosures: T.M. Gerner, None; A.E. Wall, None; E.M. Napoliello, None; L.D. Flowers,
None; G.F. Eden, None.