Theta-gamma coding

A candidate neural syntax for memory in which items are represented by gamma-band (roughly 30-100 Hz) assemblies whose timing is organized by the phase of a slower theta rhythm (roughly 4-8 Hz): successive gamma cycles nested within one theta cycle carry an ordered sequence of items, giving a mechanism for encoding order and for holding several items in working memory. Cross-frequency (theta-gamma phase-amplitude) coupling is its principal empirical signature.

For cognitive prosthetics, theta-gamma structure matters two ways. As a readout, the strength and organization of coupling index memory and workload states. As a write target, stimulation delivered at a particular theta phase, or theta-burst stimulation matching the endogenous rhythm, engages plasticity and memory more effectively than phase-blind stimulation — motivating phase-dependent stimulation. The framework is influential but not universally accepted, and its human evidence is largely correlational.