In a recent study of seniors who performed particularly well on fluid thinking tests, researchers found that brain areas at the back of the brain (posterior cingulate) seemed to trump the classical executive areas in the front. As found in a different study involving superior IQ kids, cortical thickness correlated well with the strength of cognitive performance.
The posterior cingulate is an interesting area because it is associated with personal or autobiographical memory. It's interesting to think that strong autobiographical learners may be more fluid with their thinking because they have a richer reservoir of personal stories and individual contexts (unlike impersonal dictionary of semantic knowledge).
Actually, many experts have argued back and forth about where intelligence resides in the brain. Some strongly believe its the frontal lobes (frontal executive) responsible for high intelligence, but this study suggests we might need to be a little more fluid in our thinking about intelligence...
Cortical Thickness and Fluid Thinking Among Seniors pdf
Eide Neurolearning Blog: The Right Brain Difference: The Complex Story in Our Brains
Eide Neurolearning Blog: The Blessings and the Burdens of High IQ
Nielsen2003Posterior.pdf>Mining the Posterior Cingulate pdf
Dissociating medial frontal and posterior cingulate activity during self-reflection