Impaired two-tone processing at rapid rates in male rats with induced microgyria

We previously reported that adult male rats with bilateral induced microgyr ia exhibit deficits in rapid auditory processing, which appear similar to a uditory processing deficits seen in individuals with developmental language disabilities. The current study was designed to further elaborate that fin ding using an improved paradigm in which stimulus duration was uncoupled fr om testing experience and learning effects. Specifically, two-tone stimuli with durations of 540, 390, 332 and 249 ms were all presented within a sing le test session in a modified operant conditioning paradigm. Subjects were tested over a period of 12 days using this variable-stimulus format. Result s confirmed microgyric male rats were impaired only in processing two-tone stimuli presented at rapid rates (i.e., 249 ms duration). Thus the current results support the previously observed link between focal malformations an d deficits in rapid auditory processing. (C) 2000 Elsevier Science B.V. All rights reserved.