Corpus callosal connection mapping using cortical gray matter parcellation and DT‐MRI

Abstract

Population maps of the corpus callosum (CC) and cortical lobe connections were generated by combining cortical gray matter parcellation with the diffusion tensor fiber tractography of individual subjects. This method is based on the fact that the cortical lobes of both hemispheres are interconnected by the corpus callosal fibers. T1-weighted structural MRIs and diffusion tensor MRIs (DT-MRI) of 22 right-handed, healthy subjects were used. Forty-seven cortical parcellations in the dorsal prefrontal cortex, ventral prefrontal cortex, sensory-motor cortex, parietal cortex, temporal cortex, and occipital cortex were semi-automatically derived from structural MRIs, registered to DT-MRI, and used to identify callosal fibers. The probabilistic connections to each cortex were mapped on entire mid-sagittal CC voxels that had anatomical homology between subjects as determined by spatial registration. According to the population maps of the callosal connections, the ventral prefrontal cortex and parts of the dorsal prefrontal cortex both project fibers through the genu and rostrum. The CC regions through which the superior frontal cortex passes extend into the posterior body. Fibers arising from the parietal lobe and occipital lobe run mainly through the splenium, while fibers arising from the sensory-motor cortex pass through the isthmus. In general, dorsal or medial cortical lobes project fibers through the dorsal region of the CC, while lateral cortical lobes project fibers through the ventral region of the CC. The probabilistic subdivision of the CC by connecting cortical gray matter provides a more precise understanding of the CC.

Anatomical location of transcallosal sensorimotor fibers in the human brain: Diffusion tensor tractography study

“…According to results of our study, the relative mean distances of the highest probabilistic locations for the precentral knob PMC, hand M1, leg M1, and precentral knob S1 TCF were to results of previous DTI studies [13][14][15][16]20].…”

“…By contrast, recent advancements in diffusion tensor tractography (DTT), derived from DTI, have now allowed visualization of the architecture and integrity of TCF in three dimensions [8][9][10][11]. Many DTT studies have reported on the topography of TCF [12][13][14][15][16][17][18][19][20][21]. However, little is known about detailed anatomical information on TCF that can be easily applied for clinical purposes [14,15,22].…”

The Neural Basis of Metacognitive Ability

“…Considerable variation in metacognitive accuracy (using type 2 SDT analysis) was found despite task performance remaining constant across individuals. Through use of structural brain imaging, this variance in metacognitive accuracy was shown to positively correlate with grey matter volume in right rlPFC (BA10; peak: 24, 65, 18; figure 4a), and greater metacognitive accuracy was associated with increased white matter integrity (fractional anisotropy) in a region of the corpus callosum known to project to the rlPFC [97]. Such findings are consistent with individual differences in localized brain structure affecting a region's functional properties [98].…”

Confirming white matter fMRI activation in the corpus callosum: Co-localization with DTI tractography

“…Fourth, structural connections between CC activation and gray matter activation may be difficult to detect in regions that have other large tracts coursing in different orientations. For example, fibres from the internal capsule and inferior longitude fasciculus may cross the callosal fibres that connect the temporal lobes (Park et al, 2008). This issue may be overcome by using advanced acquisition and analysis techniques (e.g., diffusion spectrum imaging; Wedeen et al, 2008).…”