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. Author manuscript; available in PMC: 2008 Dec 8.
Published in final edited form as: Magn Reson Med. 2008 Dec;60(6):1518–1523. doi: 10.1002/mrm.21766

Fig. 1.

Fig. 1

MT-varied BOLD fMRI responses to somatosensory stimulation. (a) Grayscale baseline EPI images from one animal are overlaid with color maps of stimulation-induced percentage change (no spatial smoothing was performed). The hemisphere contralateral to stimulation appears on the left in images. As MTR increases, baseline signal intensity (a.u. = arbitrary units) decreases, while percentage signal change (ΔSstim,MT/SMT) increases in the contralateral somatosensory area. Green square overlays show 9-pixel ROI in the somatosensory area. (b) Inter-animal comparisons within somatosensory ROIs show stimulus-induced changes to R2 [-ΔR2 = (ΔSstim,MT/SMT)/TE] vs. MTR calculated from the baseline data. The statistically-significant change in ΔR2 between target MTR values (*P < 0.01, n = 13) reflects the increasing intravascular contribution to ΔR2 with MTR. Open symbols show individual animal’s data at each MTR value for TE = 30 ms (squares connected with dashed lines) or TE = 40 ms (circles connected with solid lines), while filled diamonds show mean data, where error bars are SD.