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. 2016 Jan 1;37(7):2368–2382. doi: 10.1177/0271678X16666292

Figure 1.

Figure 1.

Se-fMRI analysis: Coronal MRI sections, statistical parametric maps, and the corresponding time courses of BOLD signal changes (ΔBOLD) elicited by electrical hindpaw stimulation at 0.5 and 0.7 mA, respectively, for C57BL/6, I/LnJ, and BALB/c mice anesthetized with isoflurane. (a) T2-weighted anatomical images with distances to Bregma and primary somatosensory hindlimb cortex contralateral to the stimulated paw (S1HL cl) indicated. Corresponding GE-EPI images displaying minimal geometrical distortions used for stimulus-evoked BOLD fMRI experiments under 1.1% isoflurane with statistical parametric maps (p ≤ 0.05 for N = 10 C57BL/6 mice, p ≤ 0.01 for N = 9 I/LnJ, and N = 9 BALB/c mice; cluster size > 10 voxels) showing widespread signal change during stimulation at 0.5 mA involving both contra- and ipsilateral (il) hemisphere. The color bar shows the respective β-values ranging from 0 to 1. Time courses of ΔBOLD in S1HL cl (blue line) and S1HL il (red line) during stimulation for the four stimulus periods of 20 s duration each (gray bar) visualize largest evoked signal changes in I/LnJ mice. Response patterns in the S1HL il and in a control region in the visual cortex V1 looked almost identical for all three strains indicating lack of specificity. Data are given as mean ± SEM. (b) Time courses of ΔBOLD in S1HL cl (blue line) and S1HL il (red line) during stimulation at 0.7 mA in N = 5 C57BL/6 mice under 1.5% isoflurane, respectively, and N = 4 I/LnJ mice under 1.5% isoflurane reflect bilateral symmetry analogous to the observations made at 1.1% isoflurane, and the BOLD responses were similarly widespread (not shown). Data are given as mean ± SEM. (c) Degree of bilaterality of the se-fMRI response in S1HL expressed by the ratio of the maximum amplitude of the BOLD response in the contra- and ipsilateral S1HL cortex (ΔBOLDmax(il)/ΔBOLDmax(cl)) did not depend on the residual reflex response to stimulation at 0.5 mA or 0.7 mA (green signs), respectively, as measure of the degree of alertness of the mice. Isoflurane levels used are noted next to the respective data points. Data are given as mean ± SEM.