Morphometric variability of precuneus in relation to gender and the hemisphere of human brain

Abstract

Precuneus, a quadrangular gyms of the medial surface of the human parietal lobe, is bound by three primary brain sulci and by superior hemispheric border. Precise encephalometric data about precuneus are important in the studies of brain lateralization, sex dimorphism, and brain functions in general. In this study, total and visible (exstrasulcal) surface area of the precuneus were measured on 50 brains of the adult persons (31 male, and 29 female), together with the investigation of its relationship to the side (left/right) and gender (sex dimorphism). The average total surface area of the precuneus was 16.07 cm2 on the right (males 16.44 cm2, females 15.27 cm2), and 15.44 cm2 on the left (males 15.67 cm2, females 14.62 cm2). The average visible (extrasulcal) surface area of cortex of precuneus was 9.97 cm2 on the left (males 10.75 cm2, females 8.91 cm2), and 9.38 cm2 on the right (males 10.25 cm2, females 8.19 cm2). Exstrasulcal surface area of the left precuneus was larger, by 0.59 cm on the average, which was not statistically significant. Total surface area of precuneus of males was significantly larger on the right (16.44 cm2) (p<0.01) than on the left (15.67 cm2). In females it was also larger on the right (15.27 cm2) than on the left (14.62 cm2), but with no statistical significance. Visible (exstrasulcal) surface area of both, (left and right precuneus of males), was highly significantly larger in comparison with the females (p<0.001). The obtained results and other facts suggested that sex dimorphism of human brain, including precuneus, was present, but not always easily observable, studied or proven in all the details.

Morphology and digitally aided morphometry of the human paracentral lobule

“…The predominance of continuous morphological type that we found (95.2%) confirms that primary and secondary areas exhibit less variability than higher order cortical areas [7], but we do not know if the same is true for morphometric differences (variability in areal sizes). We did not find statistically significant differences in the extrasulcal surface area of the PCL between males and females, but morphological and morphometric gender differences have various aspects and are more complex than usually expected [21]. We found two distinct morphological types of the human PCL with a predominance of the continuous type (95.2% of cases), the presence of the lobulo-limbic gyri in 13.1% of cases, and significantly larger PCL extrasulcal surface on the left hemispheres, both in males and females.…”

Sulcal pattern, extension, and morphology of the precuneus in adult humans

“…A survey 265 on fixed brains suggested that males have larger surface area than females, and that the right 266 side is larger than the left one (Spasojević et al, 2004). A recent MRI analysis evidenced that 267 sexual differences may be due to cortical thickness more than to surface, and that the right 268 side has larger cortical surface but smaller cortical thickness (Bruner et al, 2015a).…”

Craneología funcional y evolución humana: relaciones estructurales y organización espacial en la evolución de las áreas fronto-parietales

“…Metric data on the precuneus based on anatomical (physical) preparations are rare. A survey on fixed brains suggested that males have larger surface area than females, and that the right side is larger than the left one (Spasojević et al, 2004). A recent MRI analysis evidenced that sexual differences may be due to cortical thickness more than to surface, and that the right side has larger cortical surface but smaller cortical thickness .…”

“…In general, sulcal patterns are used as a reference for neurosurgical guidance (Ribas et al, 2006). Morphometric evaluations, in this case, may largely depend on the variable nature of the subparietal sulcus (Spasojević et al, 2004). The patterns and connections of this sulcus were addressed recently in two different studies: Gürer et al (2013) analyzed a small sample of 28 post-mortem brains and Kacar et al (2015) studied the MRIs of 200 individuals.…”

“…Precuneus dimensions are also the main difference between human and chimpanzee midsagittal brain morphology, with humans exhibiting marked expansion of this medial parietal element . The precuneus is part of the superior parietal lobules, and it is positioned medially between the somatosensory cortex and the occipital cortex, corresponding to Brodmann area 7 (see Spasojevic et al, 2004;. In adult humans its sagittal aspect has an average height of 36 mm and average length of 37 mm, and it is delimitated inferiorly by a parasagittal fold, the subparietal sulcus, with an average width of 14 mm .…”