TY - JOUR T1 - The effects of a TMS double lesion to a cortical network JF - bioRxiv DO - 10.1101/517128 SP - 517128 AU - Ian G.M. Cameron AU - Andreea Cretu AU - Femke Struik AU - Ivan Toni Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/04/23/517128.abstract N2 - Transcranial magnetic stimulation (TMS) is often used to understand the function of individual brain regions, but this ignores the fact that TMS may affect network-level rather than nodal-level processes. We examine the effects from a “double lesion” to two frontoparietal network nodes compared to the effects from single lesions to either node. We hypothesize that the absence of additive effects indicates that a single lesion is consequential to a network-level process. Twenty-three humans performed pro- (look towards) and anti- (look away) saccades after receiving continuous theta-burst stimulation (cTBS) to right frontal eye fields (FEF), dorsolateral prefrontal cortex (DLPFC) or somatosensory cortex (S1) (the control region). On a subset of trials, a TMS pulse was applied to right posterior parietal cortex (PPC). FEF, DLPFC and PPC are important frontoparietal network nodes for controlling anti-saccades. Bayesian T-tests were used to test hypotheses for additive double lesion effects on saccade behaviors (cTBS plus TMS pulse) against the null hypothesis that double lesion effects are not different than single lesion effects. We observed strong evidence (BF10 = 325.22) that DLPFC cTBS plus PPC TMS lesion enhanced impairments in ipsilateral anti-saccade amplitudes over DLPFC cTBS alone, but not over the effect of the PPC pulse alone (BF10 = 0.75). Therefore, effects were not additive, and no other evidence for additive effects was found (BF10 < 3). This suggests that saccade-control computations are distributed across this network, with some degree of compensation by PPC for the DLPFC lesion. ER -