Table 6 Clinical, preprocessing and analysis factors implicated in heterogeneity of findings for functional connectivity (patients vs controls).
Parameter | Studies with increased gamma functional connectivity (N = 4) | Studies with decreased gamma functional connectivity (N = 6) | Studies with mixed results (N = 4) | Studies with no group differences (N = 6) |
|---|---|---|---|---|
Total sample size | 147 | 179 | 168 | 260 |
Age | 29 [27 | 31.3] | 28.1 [27.3 | 40] | 40.4 [37 | 40.4] | 24 [23.5 | 36.7] |
Sex (F) | 32% [26 | 36.5] | 48% [31 | 53] | 21% [21 | 21] | 24% [23 | 37] |
Duration of illness (months) | 63.2 [43.7 | 117.1] | 24.2 [18.4 | 47.1] | 12.7 [12.7 | 12.7] | 19.3 [17.7 | 48.1] |
Severity of disease (PANSS total score) | 75.8 [70 | 78.2] | 64.6 [61.4 | 72.2] | 91 [91 | 91] | 62.1 [58 | 68] |
Medication status | Medicated: 1 | Medicated:3 | Medicated: 3 | Medicated: 4 |
Unmedicated: 2 | Unmedicated: 0 | Unmedicated: 0 | Unmedicated: 0 | |
Mixeda: 1 | Mixeda: 2 | Mixeda: 0 | Mixeda: 2 | |
Na: 0 | Na: 1 | Na: 1 | Na: 0 | |
Recording method | EEG: 4 | EEG: 3 | EEG: 4 | EEG: 3 |
MEG: 0 | MEG: 2 | MEG: 0 | MEG: 3 | |
Number of channels/sensors | 114 [32 | 194] | 45 [20 | 306] | 64 [64 | 64] | 25 [21 | 148] |
Recording duration | 5’ [3 | 8] | 7’ [5 | 12] | 4’ [4 | 5] | 7’ [5 | 10] |
Eyes open/eyes closed | Open: 0 | Open: 2 | Open: 1 | Open: 1 |
Closed: 4 | Closed: 3 | Closed: 3 | Closed: 5 | |
Na: 0 | Na: 1 | Na: 0 | Na: 0 | |
Gamma sub-band | 30–50 hz: 2 | 30–50 hz: 3 | 30–50 hz: 1 | 30–50 hz: 4 |
30–70 hz: 1 | 30–70 hz: 2 | 30–70 hz: 3 | 30–70 hz: 2 | |
30–100 hz: 1 | 30–100 hz: 1 | 30–100 hz: 0 | 30–100 hz: 0 | |
Artifact correction method | ICA: 1 | ICA: 0 | ICA: 0 | ICA: |
ICA+other: 1 | ICA+other: 1 | ICA+other: 3 | ICA+other: | |
Other: 2 | Other: 4 | Other: 1 | Other: | |
Na: 0 | Na: 1 | Na: 0 | Na: | |
Absolute or relative power | Absolute: 2 | Absolute: 4 | Absolute: 1 | Absolute: 2 |
Relative: 1 | Relative: 1 | Relative: 0 | Relative: 1 | |
Na: 1 | Na: 1 | Na: 3 | Na: 3 | |
Brain region | Whole brain: 1 | Whole brain: 3 | Whole brain: 0 | / |
Multiple: 3 | Multiple: 3 | Multiple: 4 | ||
Frontal: 0 | Frontal: 0 | Frontal: 0 | ||
Temporal: 0 | Temporal: 0 | Temporal: 0 | ||
Central: 0 | Central: 0 | Central: 0 | ||
Parietal: 0 | Parietal: 0 | Parietal: 0 | ||
Occipital: 0 | Occipital: 0 | Occipital: 0 | ||
Source localization method | LORETA: 2 | LORETA: 2 | LORETA: 1 | LORETA: 1 |
Equivalent current dipole: 0 | Equivalent current dipole: 0 | Equivalent current dipole: 0 | Equivalent current dipole: 0 | |
Minimum norm estimates: 0 | Minimum norm estimates: 0 | Minimum norm estimates: 0 | Minimum norm estimates: 2 | |
DICS: 0 | DICS: 0 | DICS: 0 | DICS: 0 | |
BESA: 0 | BESA: 0 | BESA: 0 | BESA: 0 | |
Others: 0 | Others: 1 | Others: 0 | Others: 1 | |
Sensor-level spectral power vs source estimates | Sensor: 2 | Sensor: 3 | Sensor: 3 | Sensor: 2 |
Source: 2 | Source: 3 | Source: 0 | Source: 4 | |
Both: 0 | Both: 0 | Both: 1 | Both: 0 | |
Functional connectivity method: | Phase lag index: 0 | Phase lag index: 2 | Phase lag index: 3 | Phase lag index: 2 |
Coherence: 1 | Coherence: 2 | Coherence: 0 | Coherence: 0 | |
Envelope: 0 | Envelope: 0 | Envelope: 0 | Envelope: 2 | |
Various: 0 | Various: 1 | Various: 1 | Various: 0 | |
Others: 3 | Others: 1 | Others: 0 | Others: 2 |
