Theta-Nested Gamma Oscillations in Next Generation Neural Mass Models

Area of Science:

• Computational Neuroscience
• Neural Oscillations
• Brain Dynamics

Background:

• Theta-nested gamma oscillations are crucial for information processing across brain scales.
• Previous experiments used optogenetics to mimic cross-frequency coupling (CFC) in vivo.
• Replicating these findings requires models that capture macroscopic neural network dynamics.

Purpose of the Study:

• To develop and analyze a new class of neural mass models for simulating spiking neural networks.
• To investigate the emergence and properties of theta-nested gamma oscillations in two network configurations: PING and ING.
• To compare model predictions with experimental results on theta-gamma cross-frequency coupling.

Main Methods:

• Utilized a novel class of neural mass models capable of reproducing spiking neural network dynamics.
• Simulated two network setups: Pyramidal Interneuronal Network Gamma (PING) and Interneuronal Network Gamma (ING).
• Applied sinusoidal theta-frequency forcing near a Hopf bifurcation to induce oscillations.

Main Results:

• Theta-nested gamma oscillations emerged in both PING and ING models under theta forcing, exhibiting phase-amplitude coupling.
• Two types of nested oscillations were identified: perfectly locked (periodic) and imperfectly locked (quasi-periodic/chaotic), with locked states more frequent in ING.
• Model results align with experiments showing amplitude modulation by theta phase, and increased gamma power/peak frequency with forcing amplitude; however, gamma peak frequency did not increase with theta frequency alone.

Conclusions:

• The developed neural mass models successfully reproduce key features of theta-nested gamma oscillations observed experimentally.
• Both PING and ING mechanisms generate theta-nested gamma oscillations with similar characteristics.
• The model provides a framework for understanding information transfer mechanisms and discrepancies with experimental findings require further investigation into stimulation parameters.