We present a geometrically constrained framework for mesoscopic electromagnetic (EM) modes in cortical tissue and derive three quantitative, falsifiable predictions for transcranial magnetic stimulation (TMS). The approach treats cortical dynamics in terms of a coarse-grained effective field whose behavior is governed by confinement within the finite thickness of the cortex (d ∼ 3mm). We show that this slab geometry induces dimensional reduction below a crossover scale L∗ ∼ d/π ∼ 1 mm, independent of microscopic parameters. The resulting dynamics yield: (1) phase-dependent disruption thresholds tied to gamma oscillations, (2) frequency-selective disruption with narrow bandwidth, and (3) recovery times independent of stimulus strength above threshold. Each prediction includes explicit falsification criteria and is testable using existing TMS–EEG protocols.
Smith, David P. (David Paul), 1956- (Sun,) studied this question.