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Charles Liu, Li-Hung Chang, Yina Tsai, Dong-Wha Kang, Yuka Sasaki, Takeo Watanabe; Changes in white matter in young adults associated with perceptual learning. Journal of Vision 2011;11(11):991. doi: 10.1167/11.11.991.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual learning (PL) in the texture discrimination task (TDT) is specific to the presented location of the trained target (Karni & Sagi, 1991). This specificity has been supported by BOLD signal changes in the trained region of V1 (eg., Yotsumoto et al., 2008). However, little research has examined whether corresponding structural changes occur together with the functional activation changes. We used the TDT to investigate structural plasticity in visual PL. A previous, related study (Yotsumoto et al., 2009, VSS) compared white matter changes in younger and older subjects over 3 training sessions, and found changes in older subjects, but not younger subjects. Here, we tested only younger subjects over a longer period of training. Seven healthy adult subjects (22–30 years) were tested; each subject completed 14 training sessions. The subjects also underwent 4 MRI sessions at various timepoints during training: pre, post-1-day, post-6-days, and post-14-days training. We measured fractional anisotropy (FA) derived from diffusion tensor imaging (DTI). FA indexes the degree of directionality of water diffusion, and reflects the microstructural properties of white matter tracts. FA values were obtained in the white matter below the visual cortical area that retinotopoically corresponded to the trained location and an untrained location. After 6 and 14 days of training, most subjects showed a relative increase in FA in the trained region compared to the untrained region. However, this increase appears to be restricted to the white matter volume underlying V2, rather than that of V1. These initial findings suggest that although structural changes associated with perceptual learning occur more easily with older subjects (Yotusmoto et al, 2009), longer training leads to structural changes in the younger brain. Similarly to the results with older people, the brain regions associated with structural changes may be different from those associated with functional changes.
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