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72 CHARACTERISTICS OF BRAIN AND BEHAVIORNotably, however, results from the longitudinal analyses revealed prominent graymatter thinning in right frontal and bilateral parieto-occipital regions, where subjectslost approximately 0.1 to 0.2 mm of cortical gray matter thickness per year.Gray matter thickness increased only in perisylvian language regions bilaterally(Wernicke’s area in the left) and in the left inferior frontal gyrus (Broca’s area;see figure 3-9) at a rate of approximately 0.05 to 0.15 mm per year. Statisticalmaps of local brain size changes revealed prominent growth in prefrontal cortices,as well as in temporal and occipital regions bilaterally (see figure 3-10). Mapsof the average rate of change revealed brain growth at a rate of 0.4 to 1.0 millimeterper year in these regions. Patterns of brain growth and gray matter thinning infrontal and parieto-occipital brain regions, along with gray matter thickness increasesvirtually exclusive to language regions are likely related to the acquisitionof new cognitive skills, such as reading, and fine tuning of previously acquiredskills that tend to occur between 5 and 12 years of age. These results have promptednew investigations of cognitive and functional correlates of cortical thicknessincreases in language cortices in normally developing children, and these studiesare currently under way.In order to assess behavioral correlates of gray matter thickness change,we conducted analyses to correlate change in gray matter thickness with changein children’s performance on the WISC-III Vocabulary subtest (raw scores)(Wechsler, 1991). Maps of the correlation between these two change measuresare shown in figure 3-11, highlighting the predominant left hemisphere relationship.Permutation tests (conducted to correct for multiple comparisons) were conductedwithin lobar regions of interest, revealing significant relationships only inthe left dorsal frontal (p = 0.045) and left parietal region (p = 0.030). In these regions,cortical thinning was associated with improvement on the cognitive test.CPM Studies in Children With Fetal Alcohol SyndromeRecent volumetric and VBM studies have confirmed brain morphologic abnormalitiesin children prenatally exposed to alcohol and have allowed a more detailed accountof some of the subtler structural dysmorphology previously observed in thesesubjects in postmortem studies. Volumetric studies have revealed prominent reductionof parietal lobe volume that is above and beyond the generalized microcephalyobserved in these subjects. They have also shown that white matter hypoplasia wasmore significant than gray matter hypoplasia, and relative sparing of hippocampalvolume was noted (Archibald et al., 2001). In another study of the same alcohol-exposed(ALC) subjects assessed in the volumetric studies, VBM analyses were conductedin which brain tissue abnormalities in the whole brain were analyzed at onceon a voxel-by-voxel basis. Results from this study (Sowell et al., 2001c) complementedfindings from the volumetric studies revealing abnormalities most prominently in the