Table 1.
Variance (%) of the Φnoise‐regressor accounted by instrumental noise, physiological noise, and stimulus regressor
| ROIVC | ROIGM | |||
|---|---|---|---|---|
| TASK | REST | TASK | REST | |
| Drifts | 30.10 (7.83)a | 25.85 (7.04) | 32.09 (8.59) | 27.21 (7.49) |
| Respiratory cycleb | 21.42 (4.90) | 16.52 (6.77) | 20.15 (6.05) | 16.16 (6.74) |
| Cardiac cycle | 1.00 (0.73) | 0.32 (0.26) | 1.65 (0.86) | 0.59 (0.43) |
| Respiratory volume rate | 0.67 (0.34) | 2.42 (0.71) | 0.89 (0.54) | 2.44 (0.69) |
| Cardiac rate | 0.86 (0.32) | 1.67 (0.55) | 0.81 (0.31) | 1.59 (0.55) |
| Stimulus regressor | 0.24 (0.12) | N/A | 0.04 (0.08) | N/A |
| Residual noisec | 45.71 (8.50) | 53.22 (5.14) | 44.37 (8.19) | 52.01 (5.61) |
a
Mean (standard error) across six subjects of the average value across voxels of each ROI (VC = visual cortex, GM = gray matter).
b
Four RETROICOR regressors were used to model effects related to the phase of the respiratory cycle.
c
Residual noise might include thermal noise, noise related to motion correction (processing step applied afterwards), and residual uncorrected signal fluctuations due to instrumental noise, physiological noise, and task related neuronal processes.