When the Correlation of the channels option is enabled:
- A spectrogram is computed for the current channel in panel 1.
- A spectrogram is computed for the selected channel in panel 2.
- The cross-spectrum is computed:
P_cross = (P1 .* conj(P2)).^0.7
Interpretation: Shows the synchrony of frequency components between two channels.
Physiological meaning:
Correlation between channels shows how synchronously two brain areas operate at specific frequencies. If two areas are synchronized at a certain frequency, they are “communicating” with each other. This may indicate a functional connection between the regions.
Different frequencies may have different degrees of synchrony:
- Synchronization in alpha: the regions are relaxed together
- Synchronization in beta: the regions are actively working together (for example, during problem solving)
- Synchronization in gamma: rapid communication between regions; information binding
Practical significance:
- Synchronization abnormalities may indicate connectivity problems.
- Very high synchronization (>0.6) may indicate not only true connectivity, but also a common source contaminating the signal (noise or artifacts).