Grant: Discovery Grants Program - Individual

Yesterday I said to my son: ""if you want dinner tonight, you need to stop tormenting your sister."" For order to be restored, he needs to draw the correct logical inference. Our lab has been studying the underlying brain mechanisms involved in successfully drawing such inferences. Over the years we have looked at how issues of familiarity of reasoning material, the presence of uncertainty, the presence of conflict, and the presence of emotionally laden content dynamically reconfigure the neural systems engaged in reasoning processes. In the present set of studies we propose to further this line of research in three ways. First, we propose to take a closer look at the issue of transitivity (A >B; B >C; A >C.), a very basic cornerstone of logical inference. In particular, some labs have been reporting a critical role for right anterior lateral prefrontal cortex (BA 10) in relational integration, while our own work is pointing to the involvement of parietal cortex (BA 40/7). We propose to undertake several studies to understand the relative contributions of frontal and parietal cortex in transitive inference. Second, there is the intriguing question of whether there are any sex differences in the recruitment of brain areas for logical reasoning. There is no evidence for sex differences in actual reasoning abilities. But logical reasoning, in particular transitive inference, involves visuospatial manipulation. There are reasons to believe that males and females utilize different strategies for spatial navigation tasks. It is possible that males and females may utilize different neural systems in logical inference tasks while arriving at the same conclusion. We propose several experiments to look at this issue. Third, all studies to date looking at the neural basis of logical reasoning involve measuring the bold response with fMRI as subjects are engaged in the reasoning task. We propose to argument these studies with volumetric MRI analyses, whereby, we correlate participants ability to engage in transitive inference with relative grey matter cortical density in parietal and frontal lobe regions. These studies will further our basic understanding of the neural basis of reasoning.