| The medial prefrontal cortex (mPFC) has been implicated in various attentional functions. Four experiments were performed to further examine the involvement of mPFC subregions in the allocation of attention by contrasting their roles in attention for action and attention for learning. In an extension of the associative learning theory of Pearce & Hall (1980), the behavioral hypothesis guiding these experiments was that cues that consistently predicted future events would control attention for action more than inconsistent predictors, but that inconsistent predictors would control more attention for learning.;In Experiments 1 and 2a, multiple choice reaction time (MCRT) tasks were used to assess rats' distribution of attention for action. Operant nosepoke responses to some visual cues were consistently (100%) reinforced (CRF) with food, whereas responses to other cues were partially (50%) reinforced (PRF). Dorsal and sham mPFC lesioned rats directed correct responding in favor of CRF cues, but ventral mPFC lesioned rats showed equal levels of correct responding to CRF and PRF cues. Nevertheless, all three groups chose CRF cues when given a choice between a CRF and a PRF cue. Under some test conditions in which attentional demands were increased, dorsal mPFC lesioned rats failed to respond on many trials, whereas the impairment in ventral mPFC lesioned rats was manifested as an increase in response errors.;In Experiments 2b and 3, Pavlovian overshadowing and serial conditioning procedures were used to examine attention for learning. In both experiments, previously inconsistent predictors of future events controlled more action in new learning than previously consistent predictors in both sham and ventral mPFC lesioned rats, but not in dorsal mPFC lesioned rats.;Taken together, these results demonstrate roles for mPFC in attention for both action and learning, and further establish the mPFC within a larger framework of attentional neural circuits. Moreover, mPFC subregions appear to be differentially involved in some aspects of attention, although this claim must be interpreted with caution, due to large lesions and some cases of conflicting response measures. Further work with more specific lesions (both anatomically and neurochemically) would allow for clarification of mPFC subregion function in attentional processes. |
