Brain Morphology in Children With Specific Language Impairment

Abstract

The planum temporale and pars triangularis have been found to be larger in the left hemisphere than the right in individuals with normal language skills. Brain morphology studies of individuals with developmental language disorders report reversed asymmetry or symmetry of the planum, although the bulk of this research has been completed on adults with dyslexia. Pars triangularis has not been studied in the developmental language impaired population. In this study, magnetic resonance imaging (MRI) was used for quantitative comparisons of the planum temporale (Wernicke's area) and pars triangularis (Broca's area) in children with specific language impairment (SLI) and children with normal language skills. The subjects were 11 children with SLI and 19 age- and sex-matched controls between 5.6 and 13.0 years old. Each subject received a neurolinguistic battery of tests and a high resolution volumetric MRI scan. Major results were that (a) pars triangularis was significantly smaller in the left hemisphere of children with SLI, and (b) children with SLI were more likely to have rightward asymmetry of language structures. Furthermore, anomalous morphology in these language areas correlated with depressed language ability. These findings support the hypothesis that language impairment is a consequence of an underlying neurobiological defect in areas of the brain known to subserve language.

Specific Language Impairment is not Specific to Language: the Procedural Deficit Hypothesis

“…Such a shift might reasonably be expected to result in anatomical or functional changes in the temporal/temporo-parietal structures underlying declarative memory, either because of the increased use of this system, or due to competitive interactions between the two systems (see above). This may explain findings that in developmental language impairment these structures show atypical asymmetry (Cohen et al, 1989;Gauger et al, 1997;Jernigan et al, 1991), in particular due to volume increases in the right hemisphere (Plante, 1991;Plante et al, 1991). It might also explain changes in the amount of gray matter or in the gray matter density in this region (Belton et al, 2002;Watkins et al, 2002).…”

“…To our knowledge, every study that has explicitly examined frontal regions has reported frontal abnormalities (Clark and Plante, 1998a; Cohen et al, 1989;Denays et al, 1989;Gallagher and Watkin, 1997;Gauger et al, 1997;Jernigan et al, 1991; Kabani et al, 1997) (KE family: Liegeois et al, 2002;. This seems to hold especially for inferior frontal regions (Clark and Plante, 1998a; Cohen et al, 1989;Gauger et al, 1997;Jernigan et al, 1991;Lou et al, 1984) (KE family: Liegeois et al, 2002;, in particular for Broca's area (Gauger et al, 1997;Lou et al, 1984) (KE family: Liegeois et al, 2002;. In addition pre-motor frontal regions, 23 including SMA, have been implicated (KE family: Belton et al, 2002;Watkins et al, 2002).…”

“…There is also some indication of an association between SLI and abnormal cerebellar structures (Oki et al, 1999) (KE family: Belton et al., 2002;Watkins et al, 1999; but see Cohen et al, 1989). Finally, studies have reported abnormalities or atypical (a)symmetries in inferior parietal and superior temporal regions (Cohen et al, 1989;Gauger et al, 1997;Jernigan et al, 1991;Lou et al, 1984) (KE family: Belton et al, 2002;Liegeois et al, 2002), as well as in perisylvian regions more generally (Jernigan et al, 1991;Plante, 1991;Plante et al, 1991). See the Table for detailed descriptions of all studies that we are aware of that have examined regional differences in the neural substrates of individuals with developmental language disorders.…”

“…Despite the wide range of neural regions examined across studies, and the likelihood of etiological heterogeneity in the SLI populations across these studies, there appears to be consistent evidence that SLI is strongly associated with abnormalities of at least two structures: frontal cortex and the basal ganglia. To our knowledge, every study that has explicitly examined frontal regions has reported frontal abnormalities (Clark and Plante, 1998a; Cohen et al, 1989;Denays et al, 1989;Gallagher and Watkin, 1997;Gauger et al, 1997;Jernigan et al, 1991; Kabani et al, 1997) (KE family: Liegeois et al, 2002;. This seems to hold especially for inferior frontal regions (Clark and Plante, 1998a; Cohen et al, 1989;Gauger et al, 1997;Jernigan et al, 1991;Lou et al, 1984) (KE family: Liegeois et al, 2002;, in particular for Broca's area (Gauger et al, 1997;Lou et al, 1984) (KE family: Liegeois et al, 2002;.…”

Development of structure and function in the infant brain: Implications for cognition, language and social behaviour

“…The planum temporale, typically larger on the left in righthanded individuals, has long been thought to be an important substrate of left-hemispheric language lateralisation (Geschwind and Levitsky, 1968). MRI studies have shown a tendency for unusual asymmetry (i.e., right hemisphere = left hemisphere or right hemisphere >left hemisphere) of the planum temporale in participants with SLI (Gauger et al, 1997) or dyslexia (Hynd et al, 1990;Larsen et al, 1990;Flowers, 1993). Structures of the perisylvian language region other than the planum temporale have also been found to differ in LLI individuals.…”