Convergent data supports an association between disruptions of cortical neuromigration (i.e., focal cortical anomalies), anomalous morphology of the auditory thalamus (MGN), and disruptions in rapid auditory processing (RAP). Moreover, in language impaired humans, RAP deficits have been linked with impairments of language and reading, while other reports show focal cortical anomalies in human dyslexic brains. Taken together, evidence suggests that focal cortical anomalies may play a role in the etiology of auditory processing deficits and language impairments in human populations. Recently, we reported that in a rat model, double-pair bilateral microgyric male rats showed significantly more severe behavioral RAP deficits compared to single-pair microgyric littermates (who were in turn worse than shams; Peiffer et al., SFN 2003). Currently, we report preliminary findings that more severe disruptions are also seen at the thalamic level in double-pair as compared to single-pair microgyric subjects. While anal...