Four previously undefined small and shallow sulci in the lateral parieto-occipital junction (LPOJ).

a. Four example inflated (top) and pial (bottom) left hemisphere cortical surfaces displaying the 13-17 sulci manually identified in the present study. Each hemisphere contains 1–4 of the previousl undefined and variable LOC/LPOJ sulci (slocs and pAngs). Each sulcus is numbered according to the legend. b. Criteria for defining slocs and pAngs components. (i) Slocs-v is the cortical indentation between the cSTS3 and lTOS. (ii) Slocs-d is the indentation between cSTS3/cSTS2 and IPS-PO. (iii) pAngs-v is the indentation between the cSTS2 and pips. (iv) pAngs-d is the indentation between cSTS2/cSTS1 and IPS. c. The variability of the slocs and pAng components can cause them to disappear when individual surfaces are averaged together. Left to right: (i) 10 Human Connectome Project (HCP) participants, (ii) 20 HCP participants, (iii) 100 HCP participants, and iv) 650 HCP participants. The disappearance of these sulci on average surfaces, which are often used for group analyses in neuroimaging research, emphasizes the importance of defining these structures in individual hemispheres.

Maximum probability maps of the 17 sulci identified in the present study.

Maximum probability map (MPMs) for the 17 LPC/LPOJ sulci on the inflated fsaverage cortical surface (sulci: dark gray; gyri: light gray; cortical surfaces are not to scale) in the left (right surface; LH) and right (left surface; RH) hemispheres. To generate the MPMs, each label was transformed from each individual to the fsaverage surface. For each vertex, the proportion of participants for whom that vertex i labeled as the given sulcus (the warmer the color, the higher the overlap) was calculated. In the cases in which the vertices for each component overlapped, the sulcus with the highest overlap across participants was assigned to that vertex. For visual clarity, the MPMs were thresholded to 20% overlap acros participants. Sulci are numbered according to Fig. 1. These sulcal MPMs can be used to guide the definition of LPC/LPOJ sulci in future studies.

The slocs-v is morphologically, architecturally, and functionally dissociable from nearby sulci.

a. Radial plot displaying the morphological (upper metrics: depth, surface area) and architectural (lower metrics: cortical thickness, myelination) features of the slocs-v (gray), cSTS3 (blue), and lTOS (green). Each dot and solid line represents the mean. The dashed lines indicate ± standard error. These features are colored by sulcus (legend). Metrics are in standardized units. b. Radial plot displaying the connectivity fingerprints of these three sulci: the Dice Coefficient overlap (values from 0-1) between each component and individual-level functional connectivity parcellations (Kong et al., 2019).

The morphology of LPC/LPOJ sulci, including the slocs-v, is related to cognitive performance.

a. Beta-coefficients for each left hemisphere LPC/LPOJ sulcus at a range of shrinking parameter values (alpha, α). The highlighted gray bar indicates coefficients at the chosen α-level. Bottom: Cross-validated mean-squared error (MSECV) at each α level. By convention, we selected the α that minimized the MSECV (dotted line). b. Inflated left hemisphere cortical surface from an example participant highlighting the two groups of sulci—dorsal positive (orange) and ventral negative (green)—related to spatial orientation performance. c. Spearman’s correlation (rs) between the measured and the predicted spatial orientation scores from the LASSO-selected model is shown in a.

The slocs-v relative to modern functional and cytoarchitectonic parcellations in LPC/LPOJ.

a. Top: Left (LH) and right (RH) hemispheres of the inflated fsaverage surface with two areas from the modern HCP multimodal parcellation (HCP-MMP; blue; Glasser et al., 2016) relative to an MPM of the slocs-v (warm colors indicate areas with at least 20% overlap across participants; Fig. 2). Bottom: Same as top, except for two observer-independent cytoarchitectonic regions from the Julich-Brain Atlas (Amunts et al., 2020). b. Overlap between the slocs-v and each area (Methods). Each dot and solid line represents the mean. The dashed lines indicate ± standard error (left: gray; right: white).

The slocs-v relative to retinotopy.

a. Top: Left (LH) and right (RH) hemispheres of the inflated fsaverage surface displaying the probabilistic locations of retinotopic maps from over 50 individuals from Wang and colleagues (Wang et al., 2015); black outlines). The predicted slocs-v location from the MPM is overlaid in orange (as in Fig. 4). (i), (ii), and (iii) point out the retinotopic maps in the cortical expanse spanning the TOS, IPS-PO, and IPS, respectively. b. Same format as in a, but with a map of the mean R2 metric from the HCP retinotopy dataset (Benson et al., 2018) overlaid on the fsaverage surfaces (thresholded between R2 values of 10% and 90%). This metric measures how well the fMRI time series at each vertex is explained by a population receptive field (pRF) model. The mean and max R2 values for the slocs-v MPM in each hemisphere are included below each surface.

Slocs-v sulcal types.

This table displays the incidence rates of how often the slocs-v intersects with a surrounding sulcus (as a percentage; out of 71 for both hemispheres). Independent means there are no intersections. These rates are highly similar between hemispheres (r = .99, p < .0001). The LOS (lateral occipital sulcus) is not described in the main text but is a sulcus ventral to lTOS, cSTS3, and slocs-v in lateral occipital cortex (Petrides, 2019).

Slocs-d sulcal types.

This table displays the incidence rates of how often the slocs-d intersects with a surrounding sulcus (as a percentage; out of 50 in the left hemisphere and 48 in the right hemisphere). Independent means there are no intersections. These rates are highly similar between hemispheres (r = .99, p < .0001).

pAngs-v sulcal types.

This table displays the incidence rates of how often the pAngs-v intersects with a surrounding sulcus (as a percentage; out of 19 in the left hemisphere and 26 in the right hemisphere). Independent means there are no intersections. These rates are highly similar between hemispheres (r = .99, p = .0003).

pAngs-d sulcal types.

This table displays the incidence rates of how often the pAngs-d intersects with a surrounding sulcus (as a percentage; out of 8 in the left hemisphere and 11 in the right hemisphere). Independent means there are no intersections.

Differences between HCP-MMP area PGp—the area that the slocs-v co-localized with at the group and probabilistic level—and surrounding areas.

This table displays the values of PGp relative to each of the surrounding regions (details are from the Supplementary Neuroanatomical Results section in Glasser et al., 2016). For example, if PGp is less myelinated than a region that box will say “less.” The location of each region relative to PGp is in parenthesis (superior indicates the region is above PGp, etc.). If an area is blank that difference was not stated in (Glasser et al., 2016). Functional contrasts are fully capitalized.

Supralateral occipital (slocs) and posterior angular (pAng) sulci relative to classic and modern sulcal definitions—References 1.

a. Sulcal definitions from Bailey et al. (1951). The black arrow indicates a depicted, but unlabeled sulcus in the vicinity of our slocs-v. The gray arrow indicates a sulcus labeled “1” in the vicinity of our pAngs components. As Bonin et al. (1951) write: “Short, isolated dimples and sulci are given letters from a to z.” Numbers were given to rami. Note that instead of identifying the three branches of the STS, they identify additional anterior (pja) and posterior (pjp) branches of the aipsJ (what they refer to as pj). b. A depicted, but unlabeled slocs-v from the most recent atlas to include tertiary sulci from Petrides (2019). c. Depicted, but unlabeled slocs-v and slocs-d from Connolly (1950).

Supralateral occipital (slocs) and posterior angular (pAng) sulci relative to classic and modern sulcal definitions—Reference 2.

Example postmortem hemispheres from Iaria and Petrides (2007) depicting the unlabeled slocs (black arrows) and pAngs (gray arrows) components.

Supralateral occipital (slocs) and posterior angular (pAng) sulci relative to classic and modern sulcal definitions—Reference 3.

Four example postmortem hemispheres from Retzius (1896) depicting the slocs (black arrows) and pAngs (gray arrows).

Ventral supralateral occipital sulcus (slocs-v) in human hemispheres from Connolly (1950).

50 example hemispheres from Connolly (1950) depicting an unlabeled slocs-v (black arrow) 94% of the time (47/50).

All 2176 LPC/LPOJ sulcal definitions across 72 participants (144 hemispheres).

Each sulcus is displayed on the left (LH, right surfaces) and right (RH, left surfaces) inflated cortical surfaces for each participant (P) in FreeSurfer 6.0.0, with the label displayed as an outline according to the key at the top.

The slocs and pAngs ventral and dorsal components are among the smallest and shallowest structures in LPC/LPOJ.

a. Box plots displaying depth (% maximum cortical depth) as a function of sulcus (x-axis) and hemisphere [left hemisphere (lh; black) and right hemisphere (rh; white)]. Individual dots represent values for individual participants. The newly-identified slocs and pAngs ventral and dorsal components are identified with the horizontal black line. We did not include STS in these plots given that it primarily resides outside the cortical expanse of interest (i.e., LPC/LPOJ). b. Same as a, but for surface area (normalized to % cortex surface area). c. Same as a, except for cortical thickness (mm). d. Same as a, except for myelination (T1w/T2w ratio).

The three caudal rami of the superior temporal sulcus and intermediate parietal sulci are dissociable neuroanatomical structures.

a. Radial plot displaying the morphological (upper metrics: depth, surface area) and architectural (lower metrics: cortical thickness, myelination) features of the caudal rami of the superior temporal sulcus (cSTS1 to 3, light to dark blue). Each dot and solid line represents the mean. The dashed lines indicate ± standard error. These features are colored b sulcus (see key). Metrics are standardized in order to be visualized on the same axis. b. Radial plot displaying the connectivity fingerprints of these three sulci: the Dice Coefficient overlap (values from 0-1) between each component and individual-level functional connectivity parcellations (Kong et al., 2019). The networks that each sulcus overlaps with (Dice > .10 for at least one sulcus) and present inter-sulcal differences are shown. c. Same as a, except for the anterior intermediate parietal sulcus of Jensen (aipsJ; red) and posterior intermediate parietal sulcus (pips; pink). d. Same as b, except for the aipsJ and pips.