Relational Processing and the Prefrontal Cortex 1 Prefrontal Cortex Involvement in Relational Processing during Reasoning

Previous patient and neuroimaging studies have provided considerable evidence that complex reasoning tasks are associated with the prefrontal cortex (PFC). In this study, we tested the hypothesis that the process of relational integration, or considering multiple relations simultaneously, is a component process of complex reasoning that recruits PFC. We used fMRI to examine brain activation during 0-relational, 1-relational, and 2-relational problems adapted from the Raven’s Progressive Matrices (RPM), and hypothesized that PFC would be preferentially recruited by the 2-relational problem type. Event-related responses were modeled by convolving a canonical hemodynamic response function (HRF) with the response time (RT) associated with each trial. The results across different analyses revealed the same pattern: PFC activation was specific to the comparison between 2and 1-relational problems, and was not observed in the comparison between 1and 0-relational problems. These results converge with previous patient findings and demonstrate a preferential PFC recruitment during the process of relational integration. Our results extend the patient findings by identifying specific PFC subregions: The process of relational integration was associated with bilateral rostrolateral PFC (RLPFC; lateral area 10) and right dorsolateral PFC (DLPFC; areas 9 and 46). Left RLPFC showed the greatest specificity by remaining preferentially recruited during 2-relational problems even after comparisons were restricted to trials matched for RT and accuracy. The link between RLPFC and the process of relational integration may be due to the associated process of manipulating self-generated information, a process that may characterize RLPFC function. Relational Processing and the Prefrontal Cortex 3