02512nas a2200289   4500008004100000022001400041245008600055210006900141300001200210490000800222520158400230653001701814653003901831653002701870653002501897100002701922700001901949700002401968700002101992700002102013700002402034700002502058700002302083700002602106700001902132856007102151       2019                        eng d  a0165-027000aA quantitative method for evaluating cortical responses to electrical stimulation0 aquantitative method for evaluating cortical responses to electri  a67 - 750 v3113 aBackground Electrical stimulation of the cortex using subdurally implanted electrodes can causally reveal structural connectivity by eliciting cortico-cortical evoked potentials (CCEPs). While many studies have demonstrated the potential value of CCEPs, the methods to evaluate them were often relatively subjective, did not consider potential artifacts, and did not lend themselves to systematic scientific investigations. New method We developed an automated and quantitative method called SIGNI (Stimulation-Induced Gamma-based Network Identification) to evaluate cortical population-level responses to electrical stimulation that minimizes the impact of electrical artifacts. We applied SIGNI to electrocorticographic (ECoG) data from eight human subjects who were implanted with a total of 978 subdural electrodes. Across the eight subjects, we delivered 92 trains of approximately 200 discrete electrical stimuli each (amplitude 4–15 mA) to a total of 64 electrode pairs. Results We verified SIGNI's efficacy by demonstrating a relationship between the magnitude of evoked cortical activity and stimulation amplitude, as well as between the latency of evoked cortical activity and the distance from the stimulated locations. Conclusions SIGNI reveals the timing and amplitude of cortical responses to electrical stimulation as well as the structural connectivity supporting these responses. With these properties, it enables exploration of new and important questions about the neurophysiology of cortical communication and may also be useful for pre-surgical planning.10aConnectivity10aCortico-cortical evoked potentials10aElectrical stimulation10aElectrocorticography1 aCrowther, Lawrence, J.1 aBrunner, Peter1 aKapeller, Christoph1 aGuger, Christoph1 aKamada, Kyousuke1 aBunch, Marjorie, E.1 aFrawley, Bridget, K.1 aLynch, Timothy, M.1 aRitaccio, Anthony, L.1 aSchalk, Gerwin  uhttp://www.sciencedirect.com/science/article/pii/S0165027018302796