Abstract: A computer-implemented apparatus for predicting an effect of a proposed surgical strategy for treatment of epilepsy and/or epileptic seizures, configured to generate synthetic brain activity data in at least some of the nodes of a brain network model, and repeatedly: a) simulate or effect a surgical strategy comprising removal of at least one node and/or edge from said brain network and subsequently recalculate said BNI value thereof; and b) calculate a value ?BNI representative of a magnitude of change in BNI following removal of said at least one node/edge from said brain network, so as to output multiple ?BNI values, or data representative thereof, corresponding to respective multiple proposed surgical strategies, each comprising removal of respective nodes/edges or sets of nodes/edges from said brain network.