Spatial and Spectral Components of the BOLD Global Signal in Rat Resting-State Functional MRI

Table S1. Timeline of anesthetic application for each subject.

Figure S1. Analysis of the last 30 min of dexmedetomidine scans. To account for any lingering effects of isoflurane on the first 30 min of dexmedetomidine scans, we also looked at the PSD estimate and spatial correlation of the global and tissue signals in the last 30 min of these scans. For both analyses, we saw similar results to those presented in the main analysis. (A) The tissue signal consisted of a higher contribution from lower frequencies than the brain global signal, with the tissue signal having a fALFF of 0.5396 and the global signal having a fALFF of 0.5035. (B) A voxel-wise correlation to the global signal shows higher correlation to the global signal from medial brain structures, as was seen in the first 30 min. (C) The same voxel-wise analysis to the tissue signal shows lower overall correlation, as was seen in the first 30 min.

Figure S2. Correlation analysis in subject 1. This figure shows the individual voxel-wise correlation analysis to the global and tissue signals in subject 1.

Figure S3. Correlation analysis in subject 2. This figure shows the individual voxel-wise correlation analysis to the global and tissue signals in subject 2.

Figure S4. Correlation analysis in subject 3. This figure shows the individual voxel-wise correlation analysis to the global and tissue signals in subject 3.

Figure S5. Correlation analysis in subject 4. This figure shows the individual voxel-wise correlation analysis to the global and tissue signals in subject 4.

Figure S6. Correlation analysis in subject 5. This figure shows the individual voxel-wise correlation analysis to the global and tissue signals in subject 5.

Figure S7. Correlation analysis in subject 6. This figure shows the individual voxel-wise correlation analysis to the global and tissue signals in subject 6.

Figure S8. Correlation analysis in subject 7. This figure shows the individual voxel-wise correlation analysis to the global and tissue signals in subject 7.

Figure S9. Correlation analysis in subject 8. This figure shows the individual voxel-wise correlation analysis to the global and tissue signals in subject 8.

Figure S10. Spatial distribution of Power under Isoflurane. This figure shows the spatial distribution of power in the isoflurane scans over the original frequency range (0.01–0.1 Hz) and the frequency range used for dexmedetomidine and isodex (0.01–0.25 Hz). When the frequency range is expanded, the power levels throughout the brain increase by way of including more power values to the sum for each pixel. However, the distribution of power spatially does not change with the increased frequency range. In fact, the addition of more frequencies appears to increase the power in all regions proportionally so that the original spatial distribution of power is maintained.