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. 2017 Sep 12;6:e26602. doi: 10.7554/eLife.26602

Figure 4. Inter-individual differences in neurochemical response to stimulation (M1 GABA change) co-varied with changes in prism after-effect retention caused by M1 a-tDCS.

(A) Experiment 7: X-axis shows individuals' percent change in GABA concentration after M1 a-tDCS (post-pre), quantified as ratios of total creatine. Y-axis shows individuals' percent change in AE retention 24 hr after PA + tDCS (anodal-sham). Correlation (N = 10) shows quantitative covariation between the behavioural and neurochemical effects of M1 a-tDCS. Note the data pass through the origin. (B) Representative image for a single participant showing voxel placement in the hand knob region of M1 and spectral quality. Frequency spectrum labels (ppm = parts per million) indicate peaks for GABA, Glutamate (Glu), total Creatine (TCr = creatine + phosphocreatine) and N-acetylaspartate (NAA).

Figure 4—source data 1. Individual participants' magnetic resonance spectroscopy data for M1 and occipital cortex before and after stimulation.
Table shows data from Experiment 7: estimated metabolite concentrations for GABA and Glutamate, as ratios of total creatine (Cr), as analysed by LC Model, with their associated uncertainty estimates (CRLB, cramer-rao lower bound scores), and spectral quality measures of signal-to-noise ratio and linewidth for each scan, together with estimates of grey matter, white matter and cerebrospinal fluid in each measurement voxel, and partial volume-corrected metabolite estimates. The change (post-pre tDCS) in partial volume-corrected metabolite estimates was used to test for inter-individual correlation with tDCS-induced change (anodal-sham) in percent AE retention.
elife-26602-fig4-data1.xlsx (43.9KB, xlsx)
DOI: 10.7554/eLife.26602.010

Figure 4.

Figure 4—figure supplement 1. AE retention scores (%) 24 hr after PA was combined with anodal or sham tDCS in Experiment 7.

Figure 4—figure supplement 1.

Bars represent individuals and group mean ±1 SEM (N = 16). Apparently missing bars represent zero retention. Participants 1–10 also had usable MRS data and are shown in the behavior-neurochemistry correlation in Figure 4. Figure 4 plots the anodal-sham difference in retention ratios.
Figure 4—figure supplement 2. MRS data from occipital cortex voxel in Experiment 7.

Figure 4—figure supplement 2.

Representative image for a single participant showing voxel placement in the occipital cortex (control region). Frequency spectrum labels (ppm = parts per million) indicate peaks for GABA, Glutamate (Glu), total Creatine (TCr = creatine + phosphocreatine) and N-acetylaspartate (NAA).