Neocortical Dynamics at Multiple Scales: EEG Standing Waves, Statistical Mechanics, and Physical Analogs

TL;DR

This paper explores multiscale neocortical dynamics by combining physical analogs, statistical mechanics, and EEG analysis to understand how global and local processes produce observed brain wave patterns.

Contribution

It introduces a unified framework linking global boundary conditions and local cortical interactions to EEG phenomena using physical and statistical models.

Findings

Standing wave patterns explain large-scale EEG coherence.

Local cortical interactions via non-myelinated fibers produce mesoscopic dynamics.

Global and local mechanisms together account for EEG behavior across scales.

Abstract

The dynamic behavior of scalp potentials (EEG) is apparently due to some combination of global and local processes with important top-down and bottom-up interactions across spatial scales. In treating global mechanisms, we stress the importance of myelinated axon propagation delays and periodic boundary conditions in the cortical-white matter system, which is topologically close to a spherical shell. By contrast, the proposed local mechanisms are multiscale interactions between cortical columns via short-ranged non-myelinated fibers. A mechanical model consisting of a stretched string with attached nonlinear springs demonstrates the general idea. The string produces standing waves analogous to large-scale coherence EEG observed in some brain states. The attached springs are analogous to the smaller (mesoscopic) scale columnar dynamics. Generally, we expect string displacement and EEG at all scales to result from both global and local phenomena. A statistical mechanics of neocortical interactions (SMNI) calculates oscillatory behavior consistent with typical EEG, within columns, between neighboring columns via short-ranged non-myelinated fibers, across cortical regions via myelinated fibers, and also derive a string equation consistent with the global EEG model.