Abstract
Number processing is a cognitive domain particularly sensitive to prenatal alcohol exposure, which relies on intact parietal functioning. Alcohol-related alterations in brain activation have been found in the parietal lobe during symbolic number processing. However, the effects of prenatal alcohol exposure on the neural correlates of non-symbolic number comparison and the numerical distance effect have not been investigated. Using functional magnetic resonance imaging (fMRI), we examined differences in brain activation associated with prenatal alcohol exposure in five parietal regions involved in number processing during a non-symbolic number comparison task with varying degrees of difficulty. fMRI results are presented for 27 Cape Colored children (6 fetal alcohol syndome (FAS)/partial FAS, 5 heavily exposed (HE) non-sydromal, 16 controls; mean age ± SD = 11.7 ± 1.1 years). Fetal alcohol exposure was assessed by interviewing mothers using a timeline follow-back approach. Separate subject analyses were performed in each of five regions of interest, bilateral horizontal intraparietal sulci (IPS), bilateral posterior superior parietal lobules (PSPL), and left angular gyrus (left AG), using the general linear model with predictors for number comparison and difficulty level. Mean percent signal change for each predictor was extracted for each subject for each region to examine group differences and associations with continuous measures of alcohol exposure. Although groups did not differ in performance, controls activated the right PSPL more during non-symbolic number comparison than exposed children, but this was not significant after controlling for maternal smoking, and the right IPS more than children with fetal alcohol syndrome (FAS) or partial FAS. More heavily exposed children recruited the left AG to a greater extent as task difficulty increased, possibly to compensate, in part, for impairments in function in the PSPL and IPS. Notably, in non-syndromal heavily exposed children activation was impaired in the right PSPL, but spared in the right IPS. These results extend previous findings of poor right IPS recruitment during symbolic number processing in FAS/PFAS, indicating that mental representation of relative quantity is affected by prenatal alcohol exposure for both symbolic and non-symbolic representations of quantity.
Highlights
Prenatal alcohol exposure causes impairment in brain structure and function, leading to cognitive and behavioral deficits (Archibald et al, 2001; Sowell et al, 2001; Riley and McGee, 2005; Astley et al, 2009)
Using a region of interest (ROI) analysis, we recently examined brain activation patterns in the five parietal regions identified by Dehaene et al (2003) as most critical for number processing in a sample consisting of the Fetal alcohol syndrome (FAS)/partial FAS (PFAS) and control children from the Meintjes et al (2010) study and a group of nonsyndromal Heavily exposed (HE) children, which was assessed on both the proximity judgment (PJ) and exact addition (EA) tasks (Woods et al, 2015)
In a whole brain analysis (Meintjes et al, 2010), we found that control children activated the right intraparietal sulci (IPS) more than children with FAS/PFAS during a PJ task, though this region was centered more posteriorly than the right IPS ROI used in this study
Summary
Prenatal alcohol exposure causes impairment in brain structure and function, leading to cognitive and behavioral deficits (Archibald et al, 2001; Sowell et al, 2001; Riley and McGee, 2005; Astley et al, 2009). Using a region of interest (ROI) analysis, we recently examined brain activation patterns in the five parietal regions identified by Dehaene et al (2003) as most critical for number processing in a sample consisting of the FAS/PFAS and control children from the Meintjes et al (2010) study and a group of nonsyndromal HE children, which was assessed on both the PJ and EA tasks (Woods et al, 2015) During both tasks, higher levels of prenatal alcohol exposure were associated with weaker activation of the right IPS. Based on our previous studies, we expected to find increased compensatory activation in the left AG by children with FASD
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