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Human Higher Brain Functions

開催日 2014/9/13
時間 15:00 - 16:00
会場 Room H(304)
Chairperson(s) 有光 威志 / Takeshi Arimitsu (慶應義塾大学医学部小児科学教室 / Department of Pediatrics, School of Medicine, Keio University, Japan)
小西 清貴 / Seiki Konishi (順天堂大学 医学部 生理学講座 / Department of Physiology, Juntendo University School of Medecine, Japan)

The laterality of the arcuate fasciculus in early adolescence: Differential effects of shared and non-shared factors in monozygotic twins

  • O3-H-3-4
  • 山本 香弥子 / Kayako Yamamoto:1,2 酒井 邦嘉 / Kuniyoshi L Sakai:1,2 
  • 1:東京大院総合文化研相関基礎科学 / Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Japan 2:CREST, 科学技術振興機構 / CREST, Japan Science and Technology Agency, Tokyo, Japan 

With diffusion magnetic resonance imaging, it has been reported that in many of participants, the arcuate fasciculus in the right hemisphere could not be successfully reconstructed (Catani et al., 2007), which might depend on b-values and/or tracking methods. The laterality of the arcuate fasciculus has not been well investigated in adolescence, when the myelination is known to continue. In the present study with diffusion magnetic resonance imaging, we established an objective method to set regions of interest (ROIs) in the arcuate fasciculus measuring the thickness of the tract. Recruiting monozygotic twins, we further examined whether individual differences in the thickness of the tract were determined by shared/non-shared factors. Participants were in three groups: 17 junior high-school students (Junior, age: 13-14), 26 senior high-school students (Senior, age: 16-17), and 12 pairs of monozygotic twins (age:16-17). With q-ball imaging, a q-space analysis of diffusion MRI, the arcuate fasciculus was successfully reconstructed in both hemispheres in all of the participants. We measured the thickness along the tract for the length of 35 mm, and selected a 20-mm-long ROI at the most straight part of the arcuate fasciculus, i.e. with minimal standard deviation of thickness within the ROI of each participant, excluding the branching or curved parts of the tract. In both Junior and Senior groups, the thickness averaged in the left ROI was significantly larger than that in the right ROI (p<0.01), indicating a clear laterality of the arcuate fasciculus already present in early adolescence. We further tested correlations of the thickness between individuals of each twin pair. The thickness of the left arcuate fasciculus showed significant correlation (r = 0.79, p<0.005), while the correlation was not significant in the right arcuate fasciculus (r = 0.57, p>0.05). These results indicate that thickness of the left arcuate fasciculus was determined by genetic and/or environmental factors shared within twin pairs, while that of the right arcuate fasciculus was more influenced by the non-shared environmental factors.

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