Towards Deciphering the Fetal Foundation of Normal Cognition and Cognitive Symptoms From Sulcation of the Cortex

Abstract

Growing evidence supports that prenatal processes play an important role for cognitive ability in normal and clinical conditions. In this context, several neuroimaging studies searched for features in postnatal life that could serve as a proxy for earlier developmental events. A very interesting candidate is the sulcal, or sulco-gyral, patterns, macroscopic features of the cortex anatomy related to the fold topology—e.g., continuous vs. interrupted/broken fold, present vs. absent fold-or their spatial organization. Indeed, as opposed to quantitative features of the cortical sheet (e.g., thickness, surface area or curvature) taking decades to reach the levels measured in adult, the qualitative sulcal patterns are mainly determined before birth and stable across the lifespan. The sulcal patterns therefore offer a window on the fetal constraints on specific brain areas on cognitive abilities and clinical symptoms that manifest later in life. After a global review of the cerebral cortex sulcation, its mechanisms, its ontogenesis along with methodological issues on how to measure the sulcal patterns, we present a selection of studies illustrating that analysis of the sulcal patterns can provide information on prenatal dispositions to cognition (with a focus on cognitive control and academic abilities) and cognitive symptoms (with a focus on schizophrenia and bipolar disorders). Finally, perspectives of sulcal studies are discussed.

Sulcal variability in anterior lateral prefrontal cortex contributes to variability in reasoning performance among young adults

“…There was no hemispheric asymmetry in incidence rates ( p = 0.66; figure 1 ), and when only one pimfs component was present, it was equally likely to be a dorsal or ventral component (χ 2 < 2, p > .15 in both hemispheres; figure 1 ). These incidence rates were similar to those observed in children and adolescents [24], which was anticipated given that sulci are formed during gestation [3,12,55,65,66].…”

“…There was no hemispheric asymmetry in incidence rates (p = 0.66; figure 1), and when only one pimfs component was present, it was equally likely to be a dorsal or ventral component (χ 2 < 2, p > .15 in both hemispheres; figure 1). These incidence rates were similar to those observed in children and adolescents [24], which was anticipated given that sulci are formed during gestation [3,12,55,65,66]. As the pimfs is variably present among young adults, we statistically tested whether this variability was related to reasoning performance, as previously found for children and adolescents [24].…”

“…For example, RLPFC is disproportionately expanded in humans relative to non-human primates, which has been hypothesized to contribute to species differences in reasoning capacity [77,90]. Further, the presence/absence and morphology of sulci are theorized to be anatomically linked to cortical white matter [12,14,30,[91][92][93]. Given that the pimfs is rare in chimpanzees [25], the presence of left pimfs-v could reflect evolutionarily expanded white matter properties that enhance neural communication in this higher cognitive area [3,[13][14][15].…”

“…To date, relationships between the presence/absence of variable sulci and cognition have been most widely explored in the anterior cingulate cortex (ACC) [12]; here, we focus on variations in the folding of the lateral prefrontal cortex (LPFC), a highly expanded region crucial for higherlevel functions such as abstract reasoning [16][17][18][19][20][21][22]. A combination of previous findings [23][24][25] further motivated the present study, showing that a sulcus in anterior LPFC (ventral paraintermediate frontal sulcus, pimfs-v) was variably present in children and adolescents [23,24] and markedly rare in chimpanzees [25].…”

What Are the Synergies between Paleoanthropology and Brain Imaging?

“…[54], and physicists, who model the mechanical phenomena that result from these growth heterogeneities [55]. This new community also includes anatomists, who study the links between folding and the organization of cortical areas and fiber bundles [56], and computer scientists, who geometrically model the variability observed in the general population, and the specificities of developmental pathologies [34,57]. In our opinion, the progress made by this community could contribute to a better exploitation of the scarce data observed in the endocasts of the folding of extinct species.…”