Phase-amplitude coupling

Phase-amplitude coupling is a neural coding mechanism in which the amplitude of fast oscillations (typically gamma, 30-100 Hz) is modulated by the phase of slower oscillations (typically theta, 4-8 Hz). This cross-frequency coupling creates a multiplexed temporal code: the slow oscillation provides a temporal framework, and the fast oscillation provides fine-grained information within each cycle. In neural synchrony research, theta-gamma phase-amplitude coupling is a predictor of memory encoding and working memory capacity. The mechanism is thought to organize information into discrete temporal packets, with each theta cycle representing a different memory item. The functional significance extends beyond memory into cross-frequency communication across brain regions, suggesting that the brain uses multiple oscillatory timescales to create a hierarchical temporal code.