Gamma band oscillations drives information flow in theta and delta band between hippocampus and medial pre-frontal cortex

Information flow in the brain is mediated by neuronal oscillations. Prior research has shown that gamma activity considered to be most reflective of neuronal firing is nested within theta cycles. This finding has given rise to the notion that theta phase mediates the gamma oscillations and thereby paces information flow. Such findings have been observed predominantly in cases where the gamma and theta oscillations were measured from the same underlying neuronal substrate. In this article, we analyze the across region, inter-brain coupling of gamma and theta oscillations using non-directional and directional connectivity measures. We show that in this context the information flow appears to be mediated by gamma oscillations which in turn drives the theta and delta oscillations. Additionally, different bands of gamma are coupled with theta and delta bands. During task, this information flow is enhanced compared to baseline in the frequencies which are coupled. Furthermore, the connectivity measures namely cross-frequency coupling and generalized partial directed coupling are not correlated with each other suggesting that they maybe representative of different underlying neuronal mechanisms.