Interhemispheric transfer in children with heavy prenatal alcohol exposure.

Background: Prenatal alcohol exposure has long been associated with alterations in brain structure and behavioral changes. The corpus callosum can be affected by heavy prenatal alcohol exposure, and agenesis (absence) of this structure occurs more often in children with fetal alcohol syndrome than in the general population or in other developmentally delayed populations. Although the majority of children with fetal alcohol syndrome do not have agenesis of the corpus callosum, callosal area is reduced in this population, particularly in the anterior and posterior regions. However, the functional implication of these size reductions has not been examined.

Methods: The current study used a finger localization task to measure the transfer of information across the corpus callosum in children and adolescents with histories of heavy prenatal alcohol exposure and age- and sex-matched controls. In a subset of children, correlational analysis was also conducted between behavioral data and cross-sectional area of the corpus callosum.

Results: When compared with nonexposed controls, alcohol-exposed children made more errors on trials for which information had to cross the corpus callosum ("crossed" trials) than on trials for which it did not ("uncrossed" trials), and they also made more errors as the task increased in complexity. Additionally, correlations with magnetic resonance imaging data in a subset of children revealed that impairment in interhemispheric transfer was related to reductions in the size of the corpus callosum. These correlations were independent of effects expected from the relationship between corpus callosum size and general intellectual functioning alone.

Conclusions: These findings suggest that children with heavy prenatal alcohol exposure display subtle deficits in the interhemispheric transfer of information in the somatosensory domain. Such deficits in interhemispheric transfer are likely to be related to the myriad of other behavioral and cognitive impairments observed in these children.