We propose two hypotheses for the divergence of theta power and phase synchrony. Under the first model, power and synchrony increase simultaneously on the same recording contacts. However, on a background of decreased power and negligible change in synchrony amongst other contacts, averaging over time and space may obscure power increases while retaining inter-regional synchronization effects (Figure 4A, upper panel). A second possibility is that increases in theta synchrony come hand in hand with concomitant decreases in power on the same recording contacts, even as the level of narrow-band theta power is relatively increased (Figure 4A, lower panel). In a memory success contrast, both hypotheses are compatible with an observed decrease in theta power (Figure 4B) accompanying an increase in synchrony.
