Updating the sulcal landscape of the human lateral parieto-occipital junction provides anatomical, functional, and cognitive insights

Abstract

Understanding the tripartite relationship among neuroanatomy, brain function, and cognition is of major interest across neurobiological subdisciplines. Recent advances in neuroimaging have uncovered neuroanatomical structures in evolutionarily-expanded portions of the brain that are related to individual differences in brain function and cognition. Here, we explored this relationship in lateral parietal cortex (LPC), a region crucial for many higher-level cognitive abilities. To do so, we manually defined 2176 individual sulci across 144 hemispheres. We identified four small and shallow indentations of the cerebral cortex (sulci) that were previously unidentified in the lateral parieto-occipital junction (LPOJ) and LPC. One of these sulci (ventral supralateral occipital sulcus, slocs-v) is present in nearly every hemisphere, and is morphologically, architecturally, and functionally dissociable from neighboring sulci. Implementing a data-driven, model-based approach relating sulcal depth to behavior identified different relationships of ventral and dorsal LPC/LPOJ sulcal networks contributing to the perception of spatial orientation. The model identified the slocs-v, further indicating the importance of this new neuroanatomical structure. Our findings build on classic neuroanatomical theories and identify new neuroanatomical targets for future “precision imaging” studies exploring the relationship among brain structure, brain function, and cognitive abilities at the level of the individual participant.

Lateral frontoparietal functional connectivity based on individual sulcal morphology

“…We also conducted exploratory analyses testing for sulcal depth-connectivity relationships for three additional pTS that have been largely overlooked in previous studies: 1) pmfs-p (in green/purple clusters in the left/right hemispheres), which does not cluster with other pmfs components and has not – unlike them – been linked to reasoning performance, 2) aipsJ (in the LPFC-LPC purple cluster), a well-known pTS in LPC (Zlatkina and Petrides, 2014), and 3) slocs-v (small cyan cluster), a newly identified sulcus (Willbrand et al, 2023c) that was implicated with reasoning in a recent morphological study (Tsai et al, 2023). These exploratory analyses revealed significant depth–connectivity associations for bilateral aipsJ and right slocs-v ( Extended Data Figure 4-2 ).…”

“…For all three of the LPFC pTS we tested bilaterally, the depth of the sulcus in one hemisphere was positively correlated with its network centrality, controlling for age and multiple comparisons. Exploratory analyses further revealed positive depth-centrality associations for two of three LPC pTS tested: left and right aipsJ and the recently identified right slocs-v (Willbrand et al, 2023c). These anatomically informed analyses provide insights regarding the functional brain architecture underlying reasoning that can serve as a foundation for future studies across age groups and clinical populations implementing analyses that are specific to the sulcal anatomy of the individual.…”

“…Using this approach in LPFC, pmfs-a and pmfs-p were shown to be functionally distinct and to overlap with different large-scale networks (Miller et al, 2021). Further, slocs-v, a newly identified pTS in LPC, overlapped with different networks compared to nearby larger surrounding sulci (Willbrand et al, 2023c). Additionally, a recent study in macaques demonstrated different clustering based on whole-brain functional connectivity for the putative homologs of pmfs-a and pmfs-i (Amiez et al, 2023).…”

“…To investigate the network defined by the LPFC–LPC sulcal features, 42 sulci (10 LPFC and 11 LPC in each hemisphere; Table 2 ) were manually defined for each participant and hemisphere. These anatomical features were defined according to the most recent atlas by Petrides (Petrides, 2019) and our recent findings (Willbrand et al, 2023c). The anatomical locations are illustrated in Figure 1 , and all 1806 sulcal definitions in all participants can be found in Extended Data Figure 1-1 .…”

“…Additionally, seeding analyses in sulci that are variable across individuals can also provide novel insights into new clusters that are cortically distant, indicating that the presence or absence of sulci is functionally meaningful at the network level in an individual hemisphere (Lopez-Persem et al, 2019). Here, we focused on functional connectivity patterns within and between LPFC and LPC sulci during performance of a reasoning task, as recent work shows relationships between reasoning scores and morphological features of LPFC sulci, including the depths of small, shallow, and evolutionarily new sulci (termed putative tertiary sulci, or pTS, throughout the manuscript; Voorhies et al, 2021; Willbrand et al, 2023a, 2023c). We conducted four types of analyses.…”