Impaired gap detection in juvenile microgyric rats.

Previous research with adult animal models links the presence of cortical neuromigrational anomalies (i.e., microgyria similar to that found in brains of dyslexics) with rapid auditory processing (RAP) impairments. RAP impairments are in turn found in children with specific language impairment (SLI) and also in individuals with dyslexia. Gap detection, a simple measure of auditory temporal acuity, appears to be impaired in children with SLI but not in dyslexic adults, even though both groups exhibit impaired processing on more complex, rapid auditory tasks. In the current study, juvenile rats with bilateral microgyria, but not their adult counterparts, exhibited impaired detection of short duration silent gaps in white noise when compared to age-matched sham littermates. Results lend further support to: (1) an association between neuromigrational anomalies and RAP impairments; and (2) the validity of an animal model of RAP impairments associated with language disturbances in humans. Current results also support the view that auditory processing disturbances associated with cortical malformations may be evident early in development at a relatively "low" level (e.g., simple gap detection), but may require "higher-order" auditory discrimination tasks (e.g., tone sequences, phonemic discriminations) to be elicited later in life.