Localizing the rostrolateral prefrontal cortex at the individual level.

The functions of the rostrolateral prefrontal cortex (RLPFC) have recently become the target of multiple theories and empirical investigations. This region can be loosely defined as the lateral portion of Brodmann area (BA) 10. One of the challenges in testing theories about RLPFC functions is the difficulty in defining its boundaries when formulating predictions for its recruitment. Here we present a procedure that goes beyond the currently available anatomical definitions to attempt a functional localization of RLPFC. A combination of functional and anatomical criteria was employed, consistent with other localizer procedures. Functional localization was performed by comparing a relational condition involving relational matching to a control condition involving feature matching. It was expected that within an anatomically defined BA10 region, this procedure would produce functional activations in the lateral but not the medial subregions. The task was administered in the course of a single 13-min fMRI session. Results showed remarkable consistency, with all subjects activating RLPFC and activations consistently localized in the lateral part of BA10. These results demonstrate the practical feasibility of localizing RLPFC using a short procedure and a combination of functional and anatomical criteria. Such localization presents with a number of potential advantages for testing theories of RLPFC functions, including improved anatomical precision of experimental predictions, as well as the possibility of reduction in the rate of false-negative findings across studies. In addition, the results provide further support for the previously proposed functional dissociation between lateral and medial BA10.