We consider the question of evaluating causal relations among neurobiological signals. In particular, we study the relation
between the directed transfer function (DTF) and the well-accepted Granger causality, and show that DTF can be interpreted
within the framework of Granger causality. In addition, we propose a method to assess the significance of causality measures.
Finally, we demonstrate the applications of these measures to simulated data and actual neurobiological recordings.
Received: 6 June 2000 / Accepted in revised form: 4 December 2000