Temporal dynamics of information flow in the cerebral cortex

The nature of information flow from one area of the cerebral cortex to anot her is poorly understood. Frequency-dependent measures of information flow, based on multivariate autoregressive modeling of field potential time seri es, have shown promise for understanding information transactions between c ortical areas (Liang et al., Neuro Report, 11 (2000) 2875-2880). In the pre sent contribution, a time domain measure of information flow between two ar eas, called the directed transinformation (DTI), is described and applied t o investigate causal influences directly from the field potential time seri es. We show that the DTI, as a generalization of mutual information, can be measured in a rather natural way, such that the interdependence of two tim e series is the sum of flow from X to Y, flow from Y to X, and instantaneou s flow. We demonstrate the usefulness of this technique on both simulated d ata and multichannel local field potentials from macaque monkeys. Compariso n with the frequency-dependent measure is also made. (C) 2001 Elsevier Scie nce B.V. All rights reserved.