Table 4.
Summary of significant findings from studies using miscellaneous methods to assess connectivity.
| 1. Mild cognitive impairment (MCI) v. Healthy control (HC) | ||||||
|---|---|---|---|---|---|---|
| Authors (Year) | Connectivity approach |
Analysis basis† |
Recording context† |
Significant bands, network† |
Group effects |
Ref. |
| Babiloni et al. (2009) | DTF | Sensors - avg. regions | Rest - EC | Theta, alpha1, alpha2, beta1 | MCI < HC | 3 |
| Bonanni et al. (2021) | MI | Sensors – pairs, avg. regions | Rest - EC | 1–100 Hz | MCI > HC | 13 |
| Cantero et al. (2009b) | DTF | Source - swLORETA | Rest - EC | Alpha1 | MCI > HC | 17 |
| Alpha2 | MCI < HC | |||||
| Crook-Rumsey et al. (2023) | SNN | Sensors - avg. regions | Task - memory, WM | SNN connectivity, # of significant connections |
MCI < HC | 22 |
| Guo et al. (2021) | PEC | Source - custom scripts | Rest - EC | Beta | MCI < HC | 40 |
| Delta, theta | MCI > HC | |||||
| Koenig et al. (2005) | GFS | Sensors - global | Rest - EC | Beta | MCI < HC | 61 |
| Li et al. (2021) | DTF | Sensors - NA | Rest - EC | Theta global DTF, node degree, global efficiency | MCI < HC | 67 |
| Liu et al. (2012) | CMI | Sensors - pairs | Task - AO | Theta | NA | 68 |
| Movahed and Rezaeian (2022) | SL | Sensors - pairs | Rest - EC | Frontal-central, within-frontal, frontal-temporal, central-occipital, within-central | MCI < HC | 75 |
| Only P3-F7, P4-Cz |
MCI > HC | |||||
| Núñez et al. (2021) | Meta-states via IACDRP |
Source - sLORETA | Rest - EC | Alpha dwell time; alpha & beta1 modularity | MCI < HC | 79 |
| Sedghizadeh et al. (2022) | Phase-amplitude coupling | Sensors - Fz, Cz, Pz | OO | Theta-gamma, at all three sites | MCI > HC | 91 |
| Timothy et al. (2017) | Recurrence rate from CRQA | Sensors - avg. regions | Rest - EC | Widespread (Task > Rest) | MCI > HC | 101 |
| Vanneste et al. (2021) | PACFC | Source - eLORETA | Rest - EC | Theta-gamma coupling | MCI < HC | 104 |
| Wen et al. (2014) | GSI, GCI, SES | Sensors - global | Rest - EC | GSI alpha | MCI < HC | 116 |
| GCI alpha, beta1, beta2 | MCI < HC | |||||
| SES alpha | MCI < HC | |||||
| 2. Alzheimer’s disease (AD) v. Healthy control (HC) | ||||||
|---|---|---|---|---|---|---|
| Authors (Year) | Connectivity approach |
Analysis basis† |
Recording context† |
Significant bands, network† | Group effects |
Ref. |
| Babiloni et al. (2009) | DTF | Sensors - avg. regions | Rest - EC | Theta, alpha1, alpha2, beta1, beta2 | AD < HC | 3 |
| Birba et al. (2022) | WSMI | Sensors – pairs, clusters | Rest (NA) | 4-10 Hz | AD > HC | 11 |
| Blinowska et al. (2017) | DTF | Sensors - pairs | Rest - EC | Theta, alpha | AD < HC | 12 |
| Chan et al. (2013) | CMI | Sensors - pairs | Rest - EC, EO, PS | 0.5-70 Hz | AD < HC | 20 |
| Herzog et al. (2022) | DTC | Source - sLORETA | Rest - EC | ^Delta, theta, alpha, beta, gamma | AD < HC | 45 |
| Jeong et al. (2001) | CMI | Sensors - pairs | Rest - EC | 1–35 Hz | AD < HC | 52 |
| Knyazeva et al. (2013) | SES | Source - LAURA | Rest - EC | Temporal, frontal | AD < HC | 60 |
| Posterior | AD > HC | |||||
| Koenig et al. (2005) | GFS | Sensors - global | Rest - EC | Delta | AD > HC | 61 |
| Alpha, Beta | AD < HC | |||||
| Lee et al. (2010) | GSI | Sensors - global | Rest - EC | Beta1, beta2, beta3, gamma | AD < HC | 64 |
| Núñez et al. (2021) | Meta-states via IACDRP |
Source - sLORETA | Rest - EC | Alpha dwell time; alpha, beta1 modularity | AD < HC | 79 |
| Park and Reuter-Lorenz (2009) | GFS | Sensors - global | Rest - EC | Beta1, beta2, beta3, broadband | AD < HC | 80 |
| Ruiz-Gómez et al. (2019a) | AEC | Sensors - pairs | Rest - EC | Alpha, beta1 | AD < HC | 85 |
| Delta | AD > HC | |||||
| Ruiz-Gómez et al. (2021) | CC | Source - sLORETA | Rest - EC | Multiplex clustering coefficient | AD < HC | 87 |
| Multiplex global strength; path length | AD > HC | |||||
| Song et al. (2018) | GCMEV | Sensors - NA | Rest - EC | 0.5–40 Hz | AD < HC | 93 |
| Tahaei et al. (2012) | Synchronization via eigenratio | Sensors - NA | Rest - EC | Delta, alpha, beta, gamma | AD < HC | 97 |
| Tyrer et al. (2020) | DCM | Source - multiple spare priors | Task - memory | 2–30 Hz | AD < HC | 103 |
| Vyšata et al. (2015) | MI | Sensors - pairs | Rest - EC | Frontolateral | AD < HC | 111 |
| Centroparietal | AD > HC | |||||
| Yu et al. (2018) | PDI | Sensors - pairs | Rest - EC | PDI | AD > HC§ | 120 |
| Zhao et al. (2019) | ROLS, DRC, AMM | Sensors - pairs | Rest - EC, EO | <70 yrs.: Nonlinear AMM | AD < HC | 123 |
| >70 yrs.: Linear AMM, nonlinear AMM; nonlinear DRC; # of significant connections |
AD > HC | |||||
Notes: Group effects based on mean differences. Within-group effects are not shown. †see Supplementary Table S1 for study specifications and technical descriptions; ^some mixed-directionality effects were found within-study, which are categorized by the most consistent pattern; # = number; § Greater values on this metric represent lower connectivity; DBTN = Dynamic brain transition network; avg = averaged; AEC = amplitude envelope correlation; AMM = average mean magnitude; AO = auditory oddball; CC = canonical correlation; CMI = Cross-mutual information; CPSD = cross-power spectral density; CRQA = cross recurrence quantification analysis; DCM = dynamic causal modeling; DRC = dynamic range of connectivity; DTC = dual total correlation; DTF = directed transfer function; EC = eyes closed; EO = eyes open; GCMEV = generalized composite multiscale entropy vector; GCI = global clustering index; GFS = global field synchronization; GSI = global synchronization index; IACDRP = amplitude correlation-derived recurrence plots; MI = mutual information; NA = not available/specified; PACFC = phase-amplitude cross-frequency coupling; OO = olfactory odball; PDI = Permutation disalignment index; PEC = power envelope connectivity; PS = photic stimulation; Ref = reference number; ROLS = Revised orthogonal least squares; SES = S-estimator synchronization; SL = synchronization likelihood; SNN = spiking neural network; WM = working memory; WSMI = weighted symbolic mutual information.