In an n-back verbal working memory task, Diwadkar and colleagues [54] observed activation patterns that differed not only between controls and prenatal alcohol exposed subjects, but also between the alcohol-exposed subjects with and without dysmorphic facial features. As task difficulty increased, each group displayed unique activation patterns. The non-exposed controls increased activity in Broca's area; non-dysmorphic alcohol-exposed subjects exhibited increases in fronto-striatal network activation; and alcohol-exposed subjects with facial dysmorphism showed activity increases in cerebellar and parietal areas. Furthermore, the between group comparisons revealed that the non-dysmorphic children displayed greater activation of the dorsolateral prefrontal cortex, while children with facial dysmorphology had reduced activation in a specific region of Broca's area associated with sub-vocal rehearsal. These group differences in activation occurred despite a lack of difference in behavioral task performance. However, the two alcohol-exposed groups did differ in the quantity of alcohol exposure. The children in the dysmorphic group were exposed to more alcohol on average and per occasion. The differences in alcohol dosage may have contributed to the distinct activation patterns observed between the dysmorphic and non-dysmorphic alcohol-exposed groups. Regardless of the dosage, the alcohol-exposed children displayed altered activation in comparison to controls.
