title: Frequency and time-frequency analysis of intraoperative ECoG during awake brain stimulation.
abstract: Electrocortical stimulation remains the standard for functional brain mapping of eloquent areas to prevent postoperative functional deficits. The aim of this study was to investigate whether the short-train technique (monopolar stimulation) and Penfield's technique (bipolar stimulation) would induce different effects on brain oscillatory activity in awake patients, as quantified by electrocorticography (ECoG). The study population was seven patients undergoing brain tumor surgery. Intraoperative bipolar and monopolar electrical stimulation for cortical mapping was performed during awake surgery. ECoG was recorded using 1 × 8 electrode strip. Spectral estimation was calculated using a parametric approach based on an autoregressive model. Wavelet-based time-frequency analysis was then applied to evaluate the temporal evolution of brain oscillatory activity. Both monopolar and bipolar stimulation produced an increment in delta and a decrease in beta powers for the motor and the sensory channels. These phenomena lasted about 4 s. Comparison between monopolar and bipolar stimulation showed no significant difference in brain activity. Given the importance of quantitative signal analysis for evaluating response accuracy, ECoG recording during electrical stimulation is necessary to characterize the dynamic processes underlying changes in cortical responses in vivo. This study is a preliminary approach to the quantitative analysis of post-stimulation ECoG signals.
authors: Department of Neurophysiology, Foundation IRCCS San Camillo Hospital Venezia, Italy.
authors: Emanuela
authors: E
authors: Formaggio
authors: Silvia F
authors: SF
authors: Storti
authors: Vincenzo
authors: V
authors: Tramontano
authors: Agnese
authors: A
authors: Casarin
authors: Alessandra
authors: A
authors: Bertoldo
authors: Antonio
authors: A
authors: Fiaschi
authors: Andrea
authors: A
authors: Talacchi
authors: Francesco
authors: F
authors: Sala
authors: Gianna M
authors: GM
authors: Toffolo
authors: Paolo
authors: P
authors: Manganotti
keywords: AR model; ECoG; bipolar; monopolar; relative wavelet power