Development of the transcallosal motor fiber from the corticospinal tract in the human brain: diffusion tensor imaging study

Abstract

Transcallosal motor fiber (TCMF) plays a role in interhemispheric inhibition (IHI) between two primary motor cortices. IHI has been an important concept in development of the motor system of the brain. Many studies have focused on the research of the topography of TCMF, however, little is known about development of TCMF. In the current study, we attempted to investigate development of TCMF from the corticospinal tract (CST) in the human brain using diffusion tensor tractography. A total of 76 healthy subjects were recruited for this study. We reconstructed the TCMF, which was derived from the CST, by selection of two regions of interest below the corpus callosum (upper and middle pons). Termination criteria used for fiber tracking were fractional anisotropy <0.2 and three tract turning angles of <45, 60, and 75°. The subjects were classified into four groups according to age: group A (0–5 years), group B (6–10 years), group C (11–15 years), and group D (16–20 years). Significant differences in the incidence of TCMF were observed between group B and group C, and between group B and group D, with tract turning angles of 60 and 75° (p < 0.05). However, no significant differences in any tract turning angle were observed between group C and group D (p > 0.05). In addition, in terms of the incidence of TCMF, no significant differences were observed between the three tract turning angles (p > 0.05). We obtained visualized TCMF from the CST with development and found that the incidence of TCMF differed significantly around the approximate age of 10 years. As a result, we demonstrated structural evidence for development of TCMF in the human brain.

Abnormal interhemispheric inhibition in musician's dystonia – Trait or state?

“…Using diffusion tensor imaging, less fractional anisotropy in the area III of the corpus callosum and less IHI was found in preschool children compared to adults [21]. This finding is in line with a study showing a gradual maturation of the connectivity of the motor part of the callosal fibre system during childhood and adolescence [22]. …”

Development of cortical motor circuits between childhood and adulthood: A navigated TMS‐HdEEG study

“…As activation of M1 in one hemisphere sends an excitatory signal transcallosally that excites inhibitory interneurons in the contralateral M1, reducing the net excitatory output [Daskalakis et al, 2002], spreading of the interhemispheric signal has been related to the microstructure of the corpus callosum [Voineskos et al, 2010], and the facilitation of interhemispheric transfer as a function of development was interpreted to reflect the maturation of the corpus callosum [Jarczok et al, 2016]. It is generally agreed that maturation of the corpus callosum continues through adolescence into young adulthood [Barnea-Goraly et al, 2004;Chen et al, 2016;Giedd et al, 1999b;Keshavan et al, 2002;Rajapakse et al, 1996;Snook et al, 2005], although some recent studies suggest that the growth of callosal regions containing motor fibers, that is, the body and isthmus, may be complete before the age of 10 years [Cancelliere et al, 2013;Kwon et al, 2014]. It is generally agreed that maturation of the corpus callosum continues through adolescence into young adulthood [Barnea-Goraly et al, 2004;Chen et al, 2016;Giedd et al, 1999b;Keshavan et al, 2002;Rajapakse et al, 1996;Snook et al, 2005], although some recent studies suggest that the growth of callosal regions containing motor fibers, that is, the body and isthmus, may be complete before the age of 10 years [Cancelliere et al, 2013;Kwon et al, 2014].…”

“…Thus, one likely contributor to increased efficiency of signal propagation is the elaboration of the myelin sheet, which may support the functional integration of distant regions [Fair r Luna and Sweeney, 2004], as childhood and adolescent development is accompanied by the refinement of white matter connectivity between brain regions [Barnea-Goraly et al, 2004;Battino et al, 1995;Chen et al, 2016;Eluvathingal et al, 2007;Giedd et al, 1999a;Keshavan et al, 2002;Lebel et al, 2008;Rajapakse et al, 1996;Snook et al, 2005]. It is generally agreed that maturation of the corpus callosum continues through adolescence into young adulthood [Barnea-Goraly et al, 2004;Chen et al, 2016;Giedd et al, 1999b;Keshavan et al, 2002;Rajapakse et al, 1996;Snook et al, 2005], although some recent studies suggest that the growth of callosal regions containing motor fibers, that is, the body and isthmus, may be complete before the age of 10 years [Cancelliere et al, 2013;Kwon et al, 2014].…”

The Safe Area in the Parieto-Occipital Lobe in the Human Brain: Diffusion Tensor Tractography

“…However, few DTT studies on the posterior safe area have been reported (2,17). We hypothesized that the safe area in the parieto-occipital lobe could be identified using the reconstructed neural tracts for the cingulum, superior (1,3,6,7,9,10,15,16,19,24).…”