COGNITIVE-PROCESSES AND CEREBRAL CORTICAL FUNDI

HUMAN brain evolution has resulted in a large increase in cortical fol ding as a result of which 60% of the cerebral cortical mantle is burie d within sulci. Cortical regions within the sulci, and especially in t he fundal zones (fundi) at the bottom of sulci, differ from the rest o f the cortex in a number of ways with respect to anatomical and histol ogical morphology. Although physiological implications of the fundal m orphology have been discussed from time to time, and although scattere d evidence hints at a special functional role for fundi, until recentl y there have been few empirical facts to guide the inquiry into a poss ibly special physiological function of fundal zones. In this article w e review findings yielded by positron emission tomography studies show ing that the peaks of changes in neuronal activity are frequently obse rved in and near fundi. We discuss, but do not accept, the possibility that these findings reflect either the partial volume effect or the c ourse of cerebral blood vessels. Instead, because of a coarse correlat ion observed between fundal fraction (the proportion of fundally relat ed activity peaks) and the apparent cognitive complexity of the tasks probed, and in light of the anatomical evidence reviewed, we propose t he hypothesis that cortical sulcal and fundal regions play a distincti ve role in higher cognitive processing.