About: Splenium is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 62926 citations. The topic is also known as: splenium of corpus callosum.
Papers published on a yearly basis
TL;DR: Across subjects, the overall density of callosal fibers had no significant correlation withcallosal area and an increased callosal area indicated an increased total number of fibers crossing through, and this was only true for small diameter fibers, whose large majority is believed to interconnect association cortex.
Abstract: The densities of fibers of different sizes were calculated in ten regions of the corpus callosum of twenty human brains (ten females, ten males). Light microscopic examination revealed a consistent pattern of regional differentiation of fiber types in the corpus callosum. Thin fibers are most dense in the anterior corpus callosum (genu), and decrease in density posteriorly towards the posterior midbody, where they reach a minimum. Towards the posterior corpus callosum (splenium), the density of thin fibers increases again, but in the posterior pole of the callosum the density decreases locally. Large-diameter fibers show a pattern complementary to that of thin fibers, having a peak of density in the posterior midbody and a local increase of density in the posterior pole of the corpus callosum. Across subjects, the overall density of callosal fibers had no significant correlation with callosal area and an increased callosal area indicated an increased total number of fibers crossing through. Considering different fiber sizes, this was only true for small diameter fibers, whose large majority is believed to interconnect association cortex. No sex differences in fiber composition of the corpus callosum were found.
TL;DR: The midsagittal area of the corpus callosum was measured in its entirety and in seven subdivisions in a sample of 50 brains consecutively obtained from autopsies of individuals who had neuropsychological testing before death.
Abstract: The midsagittal area of the corpus callosum was measured in its entirety and in seven subdivisions in a sample of 50 brains consecutively obtained from autopsies of individuals who had neuropsychological testing before death. A 12-item test of hand preference was used as an index of the pattern of interhemispheric functional asymmetry. Callosal size was analysed for two factors: hand preference, classified as consistent-right-hand preference (CRH) versus non consistent-right-hand preference, and sex. The group of nCRH (n = 18) was found to have a larger overall callosal area, with the greatest difference occurring in the posterior body segments, especially the isthmus. The isthmus probably includes interhemispheric fibres from posterior parietal and superior temporal cortex which involves cortical regions related to functional asymmetry. The results of variation in callosal morphology are discussed as part of a possible substrate of functional asymmetry and due to variation in axonal elimination in early brain development. Sex differences were found in several aspects of callosal anatomy. (1) The difference between hand groups in the posterior body occurred in interaction with sex:handedness was a factor in callosal size in males (n = 15), but not in females (n = 35). This result is consistent with the general hypothesis of females having less clear lateralization than males. (2) Females did not have a larger overall callosum or a larger splenium, either in absolute size or size proportional to brain weight. The latter measure was considered since callosal area correlated with cerebrum weight (r = 0.48). In contrast, female of both hand groups were found to have a larger proportional isthmus compared to CRH males. (3) Of all callosal regions, only the genu and a part of the anterior body were found to be larger in absolute size in males than females. (4) Callosal size decreased with chronological age in males, but not in females.
TL;DR: DTI-based fiber tractography of healthy human subjects suggests a modification of the widely accepted Witelson scheme and a new classification of vertical CC partitions.
Abstract: Several tracing studies have established a topographical distribution of fiber connections to the cortex in midsagittal cross-sections of the corpus callosum (CC). The most prominent example is Witelson's scheme, which defines five vertical partitions mainly based on primate data. Conventional MRI of the human CC does not reveal morphologically discernable structures, although microscopy techniques identified myelinated axons with a relatively small diameter in the anterior and posterior third of the CC as opposed to thick fibers in the midbody and posterior splenium. Here, we applied diffusion tensor imaging (DTI) in conjunction with a tract-tracing algorithm to gain cortical connectivity information of the CC in individual subjects. With DTI-based tractography, we distinguished five vertical segments of the CC, containing fibers projecting into prefrontal, premotor (and supplementary motor), primary motor, and primary sensory areas as well as into parietal, temporal, and occipital cortical areas. Striking differences to Witelson's classification were recognized in the midbody and anterior third of the CC. In particular, callosal motor fiber bundles were found to cross the CC in a much more posterior location than previously indicated. Differences in water mobility were found to be in qualitative agreement with differences in the microstructure of transcallosal fibers yielding the highest anisotropy in posterior regions of the CC. The lowest anisotropy was observed in compartments assigned to motor and sensory cortical areas. In conclusion, DTI-based fiber tractography of healthy human subjects suggests a modification of the widely accepted Witelson scheme and a new classification of vertical CC partitions.
TL;DR: It is suggested that WM alterations are variable throughout the brain and that particular fiber populations within prefrontal region and PLIC are most vulnerable to age-related degeneration.
Abstract: Cerebral white matter (WM) undergoes various degenerative changes with normal aging, including decreases in myelin density and alterations in myelin structure. We acquired whole-head, high-resolution diffusion tensor images (DTI) in 38 participants across the adult age span. Maps of fractional anisotropy (FA), a measure of WM microstructure, were calculated for each participant to determine whether particular fiber systems of the brain are preferentially vulnerable to WM degeneration. Regional FA measures were estimated from nine regions of interest in each hemisphere and from the genu and splenium of the corpus callosum (CC). The results showed significant age-related decline in FA in frontal WM, the posterior limb of the internal capsule (PLIC), and the genu of the CC. In contrast, temporal and posterior WM was relatively preserved. These findings suggest that WM alterations are variable throughout the brain and that particular fiber populations within prefrontal region and PLIC are most vulnerable to age-related degeneration.
TL;DR: Preliminary observations suggest a sex difference in the shape and surface area of the human corpus callosum, and this finding could be related to possible gender differences in the degree of lateralization for visuospatial functions.
Abstract: Preliminary observations suggest a sex difference in the shape and surface area of the human corpus callosum. The sexual dimorphism is striking in the splenium, the caudal or posterior portion of the corpus callosum. The female splenium is both more bulbous and larger than the male counterpart. Since peristriate, parietal, and superior temporal fibers course through the splenium, this finding could be related to possible gender differences in the degree of lateralization for visuospatial functions.
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