Delineating prefrontal cortex region contributions to crossmodal object recognition in rats

In the present study, we assessed the involvement of the prefrontal cortex (PFC) in the ability of rats to perform crossmodal (tactile-to-visual) object recognition tasks. We tested rats with 3 different types of bilateral excitotoxic lesions: (1) Large PFC lesions, including the medial PFC (mPFC) and ventral and lateral regions of the orbitofrontal cortex (OFC); (2) selective mPFC lesions; and (3) selective OFC lesions. Rats were tested on 2 versions of crossmodal object recognition (CMOR): (1) The original CMOR task, which uses a tactile-only sample phase and a visual-only choice phase; and (2) a "multimodal pre-exposure" version (PE/CMOR), in which simultaneous pre-exposure to the tactile and visual features of an object facilitates CMOR performance over longer memory delays. Inclusive PFC lesions disrupted performance on both versions of CMOR, whereas selective mPFC damage had no effect. Lesions limited to the OFC caused delay-dependent deficits on the CMOR task, but failed to reverse the enhancement produced by multimodal object pre-exposure. This pattern of functional dissociations suggests complex, multidimensional contributions of the PFC and its subregions to crossmodal cognition.