The ASD subjects with idiosyncratic and unreliable brain responses do not all stand out in terms of motion or system artifacts
| FD | Dvars | Nyquist | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Mean (mm) | Sd (mm) | Max (mm) | Fcensor (frac) | Mean (a.u.) | Flicker (a.u.) | Avmax (a.u.) | Avmean (a.u.) | Fcensor (frac) | |
| A01 | |||||||||
| Part 1 run 1 [37] | 0.09 (1.09) [5] | 0.05 (0.58) [8] | 0.32 (0.51) [13] | 0.10 (1.59) [4] | 37.56 (0.84) [1] | 30.60 (0.19) [7] | 2.13 (0.17) [11] | 1.14 (0.04) [8] | 0.63 (2.70) [1] |
| Part 2 run 1 [37] | 0.09 (0.62) [11] | 0.04 (−0.00) [19] | 0.22 (−0.41) [28] | 0.07 (0.23) [7] | 39.31 (1.43) [1] | 23.18 (−0.15) [6] | 1.71 (−0.09) [6] | 1.09 (−0.16) [10] | 0.21 (0.52) [8] |
| Part 1 run 2 [33] | 0.10 (0.59) [14] | 0.06 (0.78) [14] | 0.50 (1.35) [10] | 0.06 (−0.46) [10] | 38.90 (0.79) [9] | 20.42 (−0.25) [6] | 1.70 (−0.20) [6] | 1.12 (−0.18) [6] | 0.04 (−0.57) [16] |
| A09 | |||||||||
| Part 1 run 1 [37] | 0.06 (−0.75) [20] | 0.04 (0.03) [17] | 0.28 (0.05) [16] | 0.02 (−0.45) [19] | 32.89 (−0.70) [22] | 13.98 (−0.32) [21] | 1.38 (−0.42) [21] | 1.08 (−0.32) [20] | 0.04 (−0.49) [20] |
| Part 2 run 1 [37] | 0.12 (2.35) [4] | 0.09 (4.19) [1] | 0.74 (4.86) [1] | 0.11 (0.62) [2] | 34.07 (−0.30) [18] | 14.57 (−0.32) [11] | 1.56 (−0.20) [11] | 1.10 (−0.08) [3] | 0.07 (−0.21) [11] |
| Part 1 run 2 [33] | 0.12 (1.23) [9] | 0.09 (2.55) [6] | 0.62 (2.44) [7] | 0.21 (1.32) [1] | 37.46 (0.34) [12] | 13.18 (−0.41) [14] | 1.44 (−0.41) [11] | 1.08 (−0.44) [12] | 0.05 (−0.53) [11] |
| A14 | |||||||||
| Part 1 run 1 [37] | 0.05 (−1.51) [29] | 0.03 (−0.49) [25] | 0.26 (−0.24) [23] | 0.04 (0.14) [14] | 34.86 (−0.05) [9] | 33.21 (0.27) [5] | 2.15 (0.19) [9] | 1.13 (−0.07) [11] | 0.25 (0.65) [15] |
| Part 2 run 1 [37] | 0.05 (−1.23) [31] | 0.04 (−0.15) [22] | 0.26 (0.01) [24] | 0.01 (−0.42) [20] | 33.95 (−0.34) [21] | 14.83 (−0.31) [9] | 1.35 (−0.36) [15] | 1.06 (−0.36) [19] | 0.04 (−0.39) [14] |
| Part 1 run 2 [33] | 0.05 (−1.56) [29] | 0.03 (−1.21) [31] | 0.25 (−0.96) [30] | 0.02 (−0.95) [17] | 33.34 (−0.95) [18] | 10.23 (−0.47) [19] | 1.40 (−0.45) [17] | 1.07 (−0.51) [19] | 0.00 (−0.69) [26] |
| A16 | |||||||||
| Part 1 run 1 [37] | 0.11 (2.33) [1] | 0.06 (1.92) [2] | 0.40 (1.43) [5] | 0.02 (−0.45) [19] | 33.20 (−0.59) [19] | 15.31 (−0.28) [16] | 1.37 (−0.43) [24] | 1.07 (−0.38) [24] | 0.02 (−0.55) [25] |
| Part 2 run 1 [37] | 0.13 (3.11) [1] | 0.07 (2.68) [7] | 0.42 (1.57) [9] | 0.04 (−0.07) [11] | 34.94 (−0.01) [11] | 12.67 (−0.35) [15] | 1.32 (−0.39) [17] | 1.07 (−0.29) [15] | 0.00 (−0.58) [21] |
| Part 1 run 2 [33] | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| A17 | |||||||||
| Part 1 run 1 [37] | 0.09 (0.80) [9] | 0.07 (2.51) [1] | 0.52 (2.91) [1] | 0.04 (0.23) [13] | 33.44 (−0.51) [15] | 26.60 (0.07) [10] | 2.06 (0.12) [16] | 1.18 (0.22) [7] | 0.37 (1.28) [12] |
| Part 2 run 1 [37] | 0.11 (1.84) [7] | 0.08 (3.18) [4] | 0.52 (2.64) [6] | 0.12 (0.84) [1] | 33.68 (−0.43) [23] | 12.43 (−0.36) [17] | 1.43 (−0.30) [14] | 1.10 (−0.14) [8] | 0.04 (−0.41) [18] |
| Part 1 run 2 [33] | 0.09 (−0.09) [21] | 0.07 (1.06) [13] | 0.50 (1.31) [13] | 0.16 (0.68) [5] | 32.44 (−1.23) [25] | 13.03 (−0.41) [17] | 1.34 (−0.49) [21] | 1.07 (−0.47) [17] | 0.06 (−0.48) [9] |
Motion and system artifacts for these ASD subjects do not consistently depart from the distribution over the rest of the subjects, ruling out simple confounds for the idiosyncratic and unreliable brain responses observed. In each cell, we give the numerical value for the artifact, then the (Z-score) with respect to the NT participants, then the [rank] with respect to the entire subject sample (all subjects; n = 37, except for Part 1 run 2, where n = 33). Values departing by more than 2 SD are underlined to help visualization. Measurements are defined as follows. We analyzed frame-by-frame displacement (FD; Power et al., 2012) of the motion parameters provided by the motion-correction procedure (applied as a preprocessing step to the EPI image series for each subject and run); specifically the mean (mean), standard deviation (sd) and maximum (max) FD values across non-censored time points (i.e. the analyzed time points, after censoring volumes with excessive DVARS). DVARS is a metric that indexes the rate of change of the BOLD signal across the brain, at each time point. At the preprocessing stage, we censored time points at which DVARS >50, following current guidelines (motion scrubbing; Power et al., 2012). We examined the fraction of censored volumes (fcensor) for each subject and the average DVARS value across the non-censored volumes (mean); both values for the distinct ASD subjects lay within the range spanned by other subjects. Finally (see Materials and Methods, MRI Data Preprocessing), our dataset was intermittently affected by a stability problem with two of the 32 elements of the head coil; we dealt with this issue at the preprocessing stage using slice-specific nuisance regressors. We computed various summary statistics on these nuisance regressors (flicker: average over slices of the cumulated fluctuations in each slice; avmax: mean over time of max value over all slices; avmean: mean over time of mean value over all slices; fcensor: fraction of time points with at least one slice above an arbitrary threshold of 2), and verified that the ASD subjects with idiosyncratic responses were within the normal range of affectedness.