Segmentation of Subcomponents within the Superior Longitudinal Fascicle in Humans: A Quantitative, In Vivo, DT-MRI Study

Abstract

Previous research in non-human primates has shown that the superior longitudinal fascicle (SLF), a major intrahemispheric fiber tract, is actually composed of four separate components. In humans, only post-mortem investigations have been available to examine the trajectory of this tract. This study evaluates the hypothesis that the four subcomponents observed in non-human primates can also be found in the human brain using in vivo diffusion tensor magnetic resonance imaging (DT-MRI). The results of our study demonstrated that the four subdivisions could indeed be identified and segmented in humans. SLF I is located in the white matter of the superior parietal and superior frontal lobes and extends to the dorsal premotor and dorsolateral prefrontal regions. SLF II occupies the central core of the white matter above the insula. It extends from the angular gyrus to the caudal-lateral prefrontal regions. SLF III is situated in the white matter of the parietal and frontal opercula and extends from the supramarginal gyrus to the ventral premotor and prefrontal regions. The fourth subdivision of the SLF, the arcuate fascicle, stems from the caudal part of the superior temporal gyrus arches around the caudal end of the Sylvian fissure and extends to the lateral prefrontal cortex along with the SLF II fibers. Since DT-MRI allows the precise definition of only the stem portion of each fiber pathway, the origin and termination of the subdivisions of SLF are extrapolated from the available data in experimental material from non-human primates.

White matter measures correlate with essential tremor severity—A pilot diffusion tensor imaging study

“…White matter alteration in ET compared to control group, as well as association with objective measures, were also reported in the SLF that is partially involved in motor functions (Makris et al., 2005). The SLF represents a complex fiber bundle that facilitates executive functioning but also encodes the position of the body in the surrounding space and monitors complex motor activities (Makris et al., 2005).…”

“…The SLF represents a complex fiber bundle that facilitates executive functioning but also encodes the position of the body in the surrounding space and monitors complex motor activities (Makris et al., 2005). Thus, our data provide compelling evidence of an involvement of primary and associative motor tracts in ET.…”

Age-related slowing of task switching is associated with decreased integrity of frontoparietal white matter

“…In the regression analyses conducted separately on data from the young and older age groups, the only ROI that showed an RT-FA association in both groups was the left SLF. Results from DTI-based tractography studies suggest that this portion of the SLF originates at or near the supramarginal gyrus (BA 40), occupies the white matter of the pericentral and frontal opercular regions and connects with lateral prefrontal regions including pLIPC (BA 44/6), and DLPFC (BA 46) (Makris et al, 2005;Catani et al, 2005). The notion that switch cost RT is influenced by microstructural properties of WM linking left lateral prefrontal and parietal cortical regions is intriguing because it is in-keeping with previous functional neuroimaging results suggesting that executive control tasks require the coordinated activity of lateral prefrontal and parietal cortical regions (Cabeza and Nyberg, 2000).…”

Heritability of regional and global brain structure at the onset of puberty: A magnetic resonance imaging study in 9‐year‐old twin pairs

“…So far, heritability of regional white matter densities in pediatric twins was unknown. The fronto-occipital fascicle (FOF) and superior longitudinal fascicle (SLF) have been suggested to be involved in visuospatial processing (FOF) and language processing (SLF) [Makris et al, 2005;. Interestingly, in an earlier study in adult twin pairs, the FOF and parts of the corpus callosum were also found to be highly heritable [Hulshoff Pol et al, 2006].…”