Theta band zero-lag long-range cortical synchronization via hippocampal dynamical relaying

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Functional brain integration relies on synchronized activity across distributed neuronal networks.
• Neural synchronization is often characterized by phase delays between signals from separate brain regions.
• The role of intermediary structures, like the hippocampus, in modulating cortico-cortical synchronization remains under-explored.

Purpose of the Study:

• To investigate the hippocampus's role in cortico-cortical theta synchronization.
• To examine how behavioral states (motor quiescence vs. active exploration) affect this synchronization.
• To model the neural dynamics underlying hippocampal-neocortical interactions.

Main Methods:

• Recurrent neural network modeling of the hippocampus and two distant neocortical sites.
• Simulating different behavioral states: motor quiescent and active exploration.
• Qualitative confirmation using local field potential recordings from corresponding brain regions.

Main Results:

• Cortico-cortical neural coupling was associated with elevated hippocampal theta oscillations in both behavioral states.
• The highest degree of synchronization between cortical regions was observed during active motor exploration.
• Model findings were qualitatively supported by experimental local field potential data.

Conclusions:

• Hippocampal theta oscillations play a crucial role in mediating long-range, zero-lag cortico-cortical synchronization in lower mammals.
• This synchronization is modulated by cognitive demands and motor activity.
• The hippocampus acts as a key relay element in coordinating large-scale brain network activity.