Table 3.
Glossary and interpretation of the effect direction of imaging measures in meta-analysis.
| EEG | |
|---|---|
| Alpha waves | Neural oscillations in the frequency range of 7.5–12.5 Hz, reflecting the resting state for the brain (relaxed awareness). Lower values are interpreted as abnormal (Huang et al., 2018). |
| Beta waves | Neural oscillations in the frequency range of 12.5−30 Hz, reflecting a state concentration and alertness. Lower values are interpreted as abnormal (Huang et al., 2018). |
|
Conflict sustained potential (Conflict SP) |
Relative slow ERP, which occurs approximately 500 ms. after stimulus onset, reflecting neural activity that response to the presence of a conflict or response selection. Higher values are interpreted as more positive (Larson et al., 2011). |
| Cortical current density | The electric current caused by neural activity per square millimetre, in which lower values are interpreted as more positive (Wollseiffen et al., 2018). |
| Contingent negative variation (CNV) | Slow negative ERP appearing during a reaction time task between a warning and an imperative stimulus, in which a greater CNV amplitude reflects a higher efficiency of stimuli processing (Grünewald-Zuberbier et al., 1978). |
| Error related negativity (ERN) | The response-locked negative deflection reflecting the response to an error of commission, which represents reinforcement learning of error detection. Lower amplitudes are interpreted as positive (Drollette et al., 2018). |
|
Initial CNV (iCNV or CNV 1) |
Early CNV wave reflecting orienting response to a stimulus and stimulus processing or evaluation. Greater amplitudes are interpreted as more positive (Loveless and Sanford, 1974). |
|
Terminal CNV (tCNV or CNV 2) |
Late CNV wave reflecting anticipatory attention for upcoming stimuli and motor preparation. Greater amplitudes are interpreted as more positive (Loveless and Sanford, 1974). |
| Theta waves | Neural oscillations in the frequency range of 4–8 Hz, reflecting meditative, drowsy and non-deep sleeping states. Higher values are interpreted as abnormal (Huang et al., 2018). |
| Theta/Alpha ratio | An index which shows the percentage of alpha versus theta waves. Higher values are interpreted as abnormal (Huang et al., 2018). |
| Theta/Beta ratio | An index which shows the percentage of beta versus theta waves. Higher values are interpreted as abnormal (Huang et al., 2018) |
| P3 amplitude | The magnitude of the P3 component, which appears approximately 300 ms after stimulus onset, reflecting the allocation of attentional resources toward the target stimulus. Higher values are interpreted as more positive (Polich, 2007). |
| P3 latency | The duration of the P3 component, which appears approximately 300 ms after stimulus onset, reflecting the processing time of the allocation of attentional resources toward the stimulus. Lower values are interpreted as more positive (Ila and Polich, 1999). |
| P3a amplitude | Positive waveform of the P3 component with short peak latency, reflecting orienting attention to novel stimuli. Higher values are interpreted as more positive (Polich, 2007). |
| P3b amplitude | Positive waveform of the P3 component during target stimulus processing, reflecting the allocation of attention during stimulus engagement. Higher values are interpreted as more positive (Polich, 2007). |
| MRI | |
| Active-state fMRI | MRI measurement that determines brain activity during cognitive tasks by detecting associated changes in BOLD signal. Changes in BOLD signal (either increased or decreased signal) are in this study interpreted as positive (Jansma et al., 2001). |
| Fractional anisotropy (FA) | DTI measurement that represents the degree to which diffusion is anisotropic, in which high FA values indicate that diffusion is greater in one direction that others, whereas low FA values indicate that diffusion is nearly equal in every direction. A high degree of myelination would cause axons to be tightly packed together and would leave less intercellular water than a low degree of myelination. Higher values are interpreted as more positive (Feldman et al., 2010). |
| Axial diffusivity (AD) | DTI measurement that represents the rate of diffusion in the direction that is parallel to the white matter tract. Higher values are interpreted as more restriction and less diffusion and are interpreted as positive (Feldman et al., 2010). |
| Mean diffusivity (MD) | DTI measurement that represents the net degree of displacement of the water molecules. Lower values are interpreted as more restriction and less diffusion and are interpreted as positive (Feldman et al., 2010). |
| Radial diffusivity (RD) | DTI measurement that represents the rate of diffusion in the direction that is perpendicular to the white matter tract. Lower values are interpreted as more restriction and less diffusion and are interpreted as positive (Feldman et al., 2010). |
| Resting-state fMRI | MRI measurement that determines brain activity during rest by detecting associated changes in the BOLD signal. Changes in BOLD signal (either increased or decreased signal) are in this study interpreted as positive (Jansma et al., 2001). |
Abbreviations: EEG, Electroencephalogram; DTI, Diffusion Tensor Imaging; fMRI, functional magnetic resonance imaging; BOLD signal, Blood-oxygen-level dependent signal.