Fronto-striatal disconnection disrupts operant delayed alternation performance in the rat.

The hypothesis that an intact corticostriatal system is necessary to mediate accurate performance of an operant version of a classic prefrontal cortical task, delayed alternation, is tested using a crossover lesion paradigm in rats. Following an initial midline transection of the genu of the corpus callosum to separate the hemispheres, crossed lesions of the striatum in one hemisphere and the prefrontal cortex in the other produced a significant and stable impairment in delayed alternation performance whereas similar lesions made on the same side had little detectable effect. Accuracy and signal detection analysis of performance across different intertrial intervals indicated that the crossed lesions induced delay-dependent deficits in working memory aspects of corticostriatal function, without changes in low levels of response bias.