Table 2.
EEG language studies.
| References | N, stroke patients | Controls | Stroke acuity at EEG collection | EEG data collection | N, channels | State in EEG collected | EEG connectivity technique | Networks/regions investigated | Collected clinical scores | Main findings |
|---|---|---|---|---|---|---|---|---|---|---|
| Jabbari et al. (65) | 53 | No | Acute | Cross-sectional | 16 | Resting | Semi quantitative analysis of slowing | Language network | PICA | Patients with pronounced slow wave activity (<8 Hz) had no or poor language recovery. |
| Szelies et al. (67) | 23 | Healthy | Subacute | Longitudinal | 19 | Resting | LC and PSA | Bilateral hemispheres | Token test | Low laterality coefficient in speech relevant regions of delta- and theta-band activity predicted good recovery. |
| Hensel et al. (25) | 11 | Healthy | Subacute and chronic | Longitudinal | 30 | Behavioral-triggered | Delta amplitude, delta dipole location and strength | Bilateral frontoparietal networks | AAT | Decreased left hemisphere delta-band activity corresponded to language recovery in the first year post-stroke, but not in the second year post-stroke. |
| Spironelli and Angrilli (69) | 17 | Healthy | Chronic | Cross-sectional | 19 | Behavioral-triggered | PSA | Bilateral hemispheres | AAT | Delta-band activity in language areas was higher in aphasics. Differential slow wave activity in various language tasks. |
| Spironelli et al. (125) | 11 | Healthy | Chronic | Cross-sectional | 38 | Behavioral-triggered | High-beta band (21–28 Hz), an index of cognitive cortical arousal | Bilateral hemispheres clustered as anterior, central, posterior | AAT | Phonological task; controls showed greater beta-band activity on the left hemisphere compared to right, whereas patients had an inverted pattern of lateralization. Reduced beta activity in perilesional areas. |
| Stojanovic et al. (68) | 32 | Healthy | Subacute | Cross-sectional | 32 | Resting | PSA | Bilateral frontoparietal networks | BDAE | Increased asymmetry in patients but decreased after 2 months of treatment in the subgroup of patients with good recovery. |
| Iyer et al. (29) | 10 | Healthy | Chronic | Longitudinal | 128 | Behavioral-triggered | Dynamic causal modeling for Event related potentials | Language Network (aMTG, pSTG, IFG, IPG, OTG) | Picture naming | Pre-treatment DCM coupling between left IPG and IFG correlated with naming improvement after treatment. Aphasics with good recovery had reduced coupling in contralateral regions post-treatment. |
| Dalton et al. (66) | 21 | Healthy | Chronic | Longitudinal | 64 | Resting | PSA | Bilateral hemispheres | WAB-AQ | Greater theta and lower beta in patients. Theta negatively correlated with language performance. |
| Kawano et al. (58) | 31 | Healthy | Subacute | Cross-sectional | 19 | Resting | Phase synchrony index (PSI) | Fronto-temporoparietal language network | Standard Language Test of Aphasia | The frontofrontal PSI was lower in aphasics and correlated positively with aphasia scores, whereas the right frontotemporal PSI was higher in aphasics and correlated negatively with aphasia scores. |
| *Nicolo et al. (70) | 24 | Healthy | Subacute | Longitudinal | 128 | Resting | FC mapping with the open-source toolbox NUTMEG | Connectivity in M1s in bilateral IFG | Geneva Bedside Aphasia Score, Nine Hole Peg, FMA-UE | Baseline beta in lesioned motor correlated with motor recovery, Beta at Broca correlated with language recovery. Global recovery associated with contralesional theta. |
*
Combined language and motor systems.
AAT, Aachen Aphasia Test; aMTG, anterior middle temporal gyrus; BDAE, Boston Diagnostic Aphasia Examination; Chronic, 6 or more months post-stroke; CNV, Contingent Negative Variation; Acute, 0–2 weeks post-stroke; IFG, inferior frontal gyrus; IPG, inferior parietal gyrus; OTG, occipitotemporal gyrus; pSTG, posterior superior temporal gyrus; Subacute, 2 weeks-6 months post-stroke; WAB-AQ, Western Aphasia Battery-Aphasia Quotient; PICA, Porch Index of Communicative Ability.