Fig 1.
Schematic diagram of the proposed model.
Each node is comprised of four neural population units: pyramidal neurons, excitatory interneurons, slow inhibtory interneurons and fast ihbitory internneurons. Each node is identical to the NMM in [36]. The nodes are mutually connected by the dynamics of the pyramidal neurons. Two independent Gaussian noise sources drive the NMM nodes.
Table 1.
Model parameters: Fixed values.
Table 2.
P parameters for each CFC simulation.
Fig 2.
Phase-Frequency Coupling (PFC) simulation.
Time domain signals are shown for visual inspection of each CFC. FO1, SO1, FO2 and SO2 are the filtered output of the Node 1 and Node 2 respectively. The frequency of FO1 varies between positive (yellow stripes) and negative (green stripes) phases of SO1. SO1 and SO2 are synchronized (i.e., cross-node PPC). Integers below the FO time waves are average numbers of FO zero crossings, which is used as an index of average frequency of each phase. Local PFC between FO1 and SO1 and cross-node PFC between FO1 and SO2 are observed.
Fig 3.
Phase-Amplitude Coupling (PAC) simulation.
The instantaneous amplitude of FO1 correlates with the synchronized SO1 and SO2. Local PAC between FO1 and SO1 and cross-node PAC between FO1 and SO2 are observable. Integers below the FO time waves indicate average number of zero crossings of FOs.
Fig 4.
Frequency-Frequency Coupling (FFC) simulation.
The frequency of FO1 and FO2 varies for the synchronized SO1 and SO2. Integers below the FO time waves are the average number of zero crossings, which is an index of average frequency of each phase. The numbers change between positive and negative phases of synchronized SO1 and SO2. Local PFC between FO1 and SO1, and between FO2 and SO2 are also observed.
Fig 5.
Amplitude-Amplitude Coupling (AAC) simulation.
The instantaneous amplitude of FO1 and FO2 correlate with the synchronized SO1 and SO2. Integers below the FO time waves indicate average number of zero crossings of FOs.
Fig 6.
Amplitude-Frequency Coupling (AFC) simulation.
The instantaneous amplitude of FO1 correlates with the synchronized SO1 and SO2. The frequency of FO2 is about constant while the frequency of FO1 varies for the synchronized SO1 and SO2. See average number of zero crossings in FOs, indicated as integers below the FO time waves.
Fig 7.
The comparison of PSDs in different forms of CFC.
PFC: Phase-Frequency Coupling, PAC: Phase-Amplitude Coupling, FFC: Frequency-Frequency Coupling, AAC: Amplitude-Amplitude Coupling, AFC: Amplitude-Frequency Coupling.