Rapid auditory processing and MGN morphology in microgyric rats reared in varied acoustic environments.

Adult male rats with induced microgyric lesions exhibit significant deficits in rapid auditory processing, as well as morphological alterations in the medial geniculate nucleus (MGN) of the thalamus. These findings are considered striking in light of similar anatomical and auditory processing anomalies in language disabled humans. Given evidence from clinical and animal studies that acoustic experience may alter sensory processing at behavioral and neurophysiological levels, the current study examined effects of developmental exposure to auditory stimulation on behavioral and anatomical indices in microgyric and sham rats. Stimulation (E7-P 70) included: (1). chronic white noise (80 dB) with standard housing; (2). 3 h/day of 78 dB filtered light classical music with social housing; or (3). standard acoustic environment (control) with standard housing. Microgyric effects on auditory processing and thalamic morphology were evident regardless of environmental condition. In sum, the effects of microgyria on brain and behavior appear to be robust, and largely orthogonal to any main effect of acoustic stimulation on auditory processing. These findings suggest that a more active form of acoustic stimulation (e.g., training) may be required to ameliorate the deleterious behavioral and anatomical consequences of focal microgyric lesions.