Information Flow and Traveling Waves show distinct cortical trajectories

Traveling waves (TWs) are a hallmark of cortical dynamics, proposed to organize neuronal activity across space and time. Yet their propagation can oppose the causal flow of information, challenging their functional interpretation. We demonstrate this using computational simulations and validate our predictions in electrophysiological recordings. We introduce the Directional Information Flow Field (DIFF), which adapts Granger causality to two-dimensional neural recordings to map directed interactions across cortical networks. In computational models, DIFF recovers the direction and sources of information flow, whereas delays and inhibition can cause TWs to propagate in opposing or orthogonal directions. We validate these findings in human and non-human primate electrophysiological recordings, revealing reversed or orthogonal flow axes, distinct spatial origins, and frequency-dependent differences in feedforward and feedback dynamics. These findings challenge the functional interpretation of TWs and establish DIFF as a complementary framework for revealing directed neural communication underlying cortical dynamics.