Sex differences in the activation of language cortex during childhood.

Sex differences have been well documented in the behavioral literature but have occurred inconsistently in the neuroimaging literature. This investigation examined the impact of subject age, language task, and cortical region on the occurrence of sex differences in functional magnetic resonance imaging. Two hundred and five (104 m, 101 f) right handed, monolingual English speaking children between the ages of 5 and 18 years were enrolled in this study. The study used fMRI at 3T to evaluate BOLD signal variation associated with sex, age, and their interaction. Children completed up to four language tasks, which involved listening to stories, prosody processing, single word vocabulary identification, and verb generation. A sex difference for behavioral performance was found for the prosodic processing task only. Brain activation in the classical left hemisphere language areas of the brain and their right homologues were assessed for sex differences. Although left lateralization was present for both frontal and temporal regions for all but the prosody task, no significant sex differences were found for the degree of lateralization. Sex x age interaction effects were found for all but the task involving single word vocabulary. However effect sizes associated with the sex differences were small, which suggests that relatively large sample sizes would be needed to detect these effects reliably.