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Phase-synchronized tACS-induced oscillatory activity modulates cortico-cortical signaling efficacy
412
Abstracts / Brain Stimulation 10 (2017) 346e540
operate in isolation, but interact with other regions through networks. Such networks can be visualized with resting state functional connectivity MRI. Here we test whether the effects of brain stimulation can be enhanced by simultaneously targeting a region and its functional network. Fifteen healthy participants received two types of transcranial direct current stimulation (tDCS): a traditional two-electrode montage targeting a single brain region (left primary motor cortex [M1]) and a novel eightelectrode montage targeting this region and its network, identified with resting state functional connectivity. As a control, 8 participants also received multifocal tDCS mismatched to this network. Network-targeted tDCS more than doubled the increase in left M1 excitability over time compared to traditional tDCS and the multifocal control. These results suggest that the effects of tDCS may be enhanced by targeting functional brain networks rather than single brain regions. Keywords: transcranial direct current stimulation, motor system, functional connectivity, resting-state fMRI [0321] FREQUENCY-SPECIFIC AFTER-EFFECTS OF TRANSCRANIAL ALTERNATING CURRENT STIMULATION (TACS) ON MOTOR LEARNING: PRELIMINARY DATA OF A SIMULTANEOUS TACS-EEG-NIRS STUDY €t A. Berger*, N.H. Pixa, M. Doppelmayr. Johannes Gutenberg Universita Mainz, Germany Introduction: Motor learning is associated with changes in synchronized oscillatory activity at alpha (8-12 Hz) and beta (12-30 Hz) frequencies. Numerous studies demonstrated the frequency-specific modulation of tACS on ongoing oscillatory activity, cortical excitability and motor behavior. However, the underlying mechanisms by which tACS is induced and persist as well as the modulation of motor learning in complex tasks remain ambiguous. Thus, we combined electroencephalography (EEG) and near-infrared spectroscopy (NIRS) during a bimanual visuomotor coordination task (2HAND, Schuhfried) to investigate electrophysiological and hemodynamic effects of tACS on motor learning. Methods: Up to now, 15 right-handed healthy participants are included in the study. They performed the required task while receiving either 10Hz tACS, 20Hz tACS or sham stimulation over the parietal cortex (P3/P4) for 20 minutes via small gel electrodes (3,14cm2 Ag/AgCl). Before and after (0 min., 30 min., 1 day, 4 days, 7 days) tACS, movement speed and accuracy of visuomotor coordination were assessed. In addition, cortical activity was examined using EEG (Starstim-Neuroelectrics, P3/P4/Fpz/Fz/Cz/Pz/Oz/ VEOG) and NIRS (NIRSport-System, NIRx, 20 channels). Results: Analyzing the motor performance, a two-way ANOVA (GROUPxTIME) revealed only a significant main effect for TIME indicating an improvement in the bimanual visuomotor coordination task (F(5,65) ¼ 11.284; p<.001; h2¼ 0,465). No significant results have been obtained for GROUP or GROUPxTIME so far. However, due to the ongoing data recording additional participants are added that might alter the results. Furthermore, in both stimulation groups an increase in alpha activity was observed in parietal regions (P3, P4, Pz) which lasts up to 30min. after stimulation. Conclusion: The present study suggests that 10Hz tACS and 20Hz tACS have similar effects on ongoing oscillatory activity. Differential effects in motor performance are expected with increased sample size. In addition, we will present the corresponding NIRS data that have not been analyzed yet. Keywords: Transcranial alternating current stimulation, Oscillatory activity, Neuromodulation, Motor learning [0323] ECT PATIENT VIEWS Y. Bloch*1, 2, M. Linder 1, N. Kallman 1, U. Nitzan 1, 2, H. Maoz 1,2, A. Segev 1, 2, M. Koubi 1, 2, I. Lurie 1, 2. 1 Sackler school of Medicine Tel Aviv University, Israel; 2 Shalvata Mental Health Center, Israel Introduction: Most studies that have evaluated patient views about Electroconvulsive therapy (ECT) reflected positive views. But, some have questioned the validity of these optimistic views, raising the importance of confounders such as the orientation of the researcher, the relationship between the patient and the research team, and the time elapsed from the treatment. We aimed to use concepts fundamental to informed consent:
comparing alternatives and choice in order to better understand conflicting results related to patient views about efficiency and satisfaction of different types of therapy and especially ECT. Methods: Four subject groups were recruited: a) those who were treated with ECT as adolescents (n¼13); b) treated with ECT as adults (n¼25); c) hospitalized as adolescents but not treated with ECT (n¼30); and d) hospitalized as adults but not treated with ECT (n¼30). All subjects were interviewed using similar questions related to their satisfaction regarding different treatment modalities, including psychotherapy, pharmacotherapy, hospitalization and ECT. Results: Both adults and adolescents viewed ECT as a legitimate and an effective form of treatment (70%). Patients that were treated with ECT had a more positive attitude toward this treatment. In comparison to other treatment modalities, ECT was considered by both age groups as the least effective form of therapy. Adults were less satisfied with the quality of explanation received about ECT, whereas adolescents reported receiving more explanations from providers (e.g., physicians, nurses, parents). Conclusion: In order to effectively evaluate patient views about ECT, it is necessary to use a framework of informed. Keywords: Adolescent, ECT, patients' views, informed consent [0326] PHASE-SYNCHRONIZED TACS-INDUCED OSCILLATORY MODULATES CORTICO-CORTICAL SIGNALING EFFICACY
ACTIVITY
r*, Y. Morishima. 1 University Hospital of Psychiatry, Switzerland; K.D. Fehe PRESTO, Japan
2
Introduction: Synchronized brain oscillations are considered a basis for inter-regional neuronal communication [1,2]. However, the causal role of inter-regional oscillatory phase-synchrony in modulating cortico-cortical signaling efficacy has so far not been directly demonstrated. Methods: To address this relationship, we employed the simultaneous use of transcranial alternating current stimulation (tACS), TMS and EEG. Through tACS we introduced theta oscillatory activity in two regions of the human frontoparietal network; the dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex (PPC). We applied 6 Hz tACS to the DLPFC and PPC simultaneously in an in-phase or anti-phase manner. For assessing resultant changes in transmission in the frontoparietal network, we simultaneously applied weak single-pulse TMS over the DLPFC at four different phases of tACS (90 , 180 , 270 , 360 ) and measured the spread of TMS-evoked EEG potentials (TEPs). The amount of current spread is modulated by the functional status of the neural network, thereby providing a measure of changes in signaling efficacy [3]. Results: We found that the amplitude of TEPs depended on the phase of the introduced 6 Hz activity during in-phase and anti-phase tACS. These phasedependent changes of TEPs quickly propagated from the DLPFC to occipital areas in the in-phase condition. However, in the anti-phase condition, phase-dependent changes in TEPs did not reach occipital areas before 100 ms after the TMS, suggesting that the tACS-induced de-synchronization of the frontoparietal network limited communication in the network. Discussion: We demonstrate that a tACS-induced state of phase-synchrony across the frontoparietal network modulates signaling efficacy in the network, with anti-phase tACS efficiently limiting signal-propagation in the network. This supports the causal role of phase-synchronized endogenous oscillatory activity in modulating inter-regional neuronal communication, in accordance with the proposed communication-through-coherence model [1]. Keywords: Transcranial Alternating Current Stimulation, Transcranial Magnetic Stimulation, Electroencephalography, Functional connectivity References [1] Engel (2001). Nat Rev Neurosci. ki (2004). Science. [2] Buzsa [3] Ilmoniemi (1997). Neuroreport. [0329] EFFECTS OF TRANSCRANIAL STATIC MAGNETIC FIELD STIMULATION (TSMS) OF THE VISUAL CORTEX ON EXPERIMENTAL PHOTOPHOBIA n*1, E. Lozano-Soto 1, S. Sabbarese 1, B.A. Strange 2, G. V. Soto-Leo 1 ejicos, Spain; Foffani , A. Oliviero 1. 1 Hospital Nacional de Parapl 2 Universidad Politecnica de Madrid, Spain
Abstracts / Brain Stimulation 10 (2017) 346e540
operate in isolation, but interact with other regions through networks. Such networks can be visualized with resting state functional connectivity MRI. Here we test whether the effects of brain stimulation can be enhanced by simultaneously targeting a region and its functional network. Fifteen healthy participants received two types of transcranial direct current stimulation (tDCS): a traditional two-electrode montage targeting a single brain region (left primary motor cortex [M1]) and a novel eightelectrode montage targeting this region and its network, identified with resting state functional connectivity. As a control, 8 participants also received multifocal tDCS mismatched to this network. Network-targeted tDCS more than doubled the increase in left M1 excitability over time compared to traditional tDCS and the multifocal control. These results suggest that the effects of tDCS may be enhanced by targeting functional brain networks rather than single brain regions. Keywords: transcranial direct current stimulation, motor system, functional connectivity, resting-state fMRI [0321] FREQUENCY-SPECIFIC AFTER-EFFECTS OF TRANSCRANIAL ALTERNATING CURRENT STIMULATION (TACS) ON MOTOR LEARNING: PRELIMINARY DATA OF A SIMULTANEOUS TACS-EEG-NIRS STUDY €t A. Berger*, N.H. Pixa, M. Doppelmayr. Johannes Gutenberg Universita Mainz, Germany Introduction: Motor learning is associated with changes in synchronized oscillatory activity at alpha (8-12 Hz) and beta (12-30 Hz) frequencies. Numerous studies demonstrated the frequency-specific modulation of tACS on ongoing oscillatory activity, cortical excitability and motor behavior. However, the underlying mechanisms by which tACS is induced and persist as well as the modulation of motor learning in complex tasks remain ambiguous. Thus, we combined electroencephalography (EEG) and near-infrared spectroscopy (NIRS) during a bimanual visuomotor coordination task (2HAND, Schuhfried) to investigate electrophysiological and hemodynamic effects of tACS on motor learning. Methods: Up to now, 15 right-handed healthy participants are included in the study. They performed the required task while receiving either 10Hz tACS, 20Hz tACS or sham stimulation over the parietal cortex (P3/P4) for 20 minutes via small gel electrodes (3,14cm2 Ag/AgCl). Before and after (0 min., 30 min., 1 day, 4 days, 7 days) tACS, movement speed and accuracy of visuomotor coordination were assessed. In addition, cortical activity was examined using EEG (Starstim-Neuroelectrics, P3/P4/Fpz/Fz/Cz/Pz/Oz/ VEOG) and NIRS (NIRSport-System, NIRx, 20 channels). Results: Analyzing the motor performance, a two-way ANOVA (GROUPxTIME) revealed only a significant main effect for TIME indicating an improvement in the bimanual visuomotor coordination task (F(5,65) ¼ 11.284; p<.001; h2¼ 0,465). No significant results have been obtained for GROUP or GROUPxTIME so far. However, due to the ongoing data recording additional participants are added that might alter the results. Furthermore, in both stimulation groups an increase in alpha activity was observed in parietal regions (P3, P4, Pz) which lasts up to 30min. after stimulation. Conclusion: The present study suggests that 10Hz tACS and 20Hz tACS have similar effects on ongoing oscillatory activity. Differential effects in motor performance are expected with increased sample size. In addition, we will present the corresponding NIRS data that have not been analyzed yet. Keywords: Transcranial alternating current stimulation, Oscillatory activity, Neuromodulation, Motor learning [0323] ECT PATIENT VIEWS Y. Bloch*1, 2, M. Linder 1, N. Kallman 1, U. Nitzan 1, 2, H. Maoz 1,2, A. Segev 1, 2, M. Koubi 1, 2, I. Lurie 1, 2. 1 Sackler school of Medicine Tel Aviv University, Israel; 2 Shalvata Mental Health Center, Israel Introduction: Most studies that have evaluated patient views about Electroconvulsive therapy (ECT) reflected positive views. But, some have questioned the validity of these optimistic views, raising the importance of confounders such as the orientation of the researcher, the relationship between the patient and the research team, and the time elapsed from the treatment. We aimed to use concepts fundamental to informed consent:
comparing alternatives and choice in order to better understand conflicting results related to patient views about efficiency and satisfaction of different types of therapy and especially ECT. Methods: Four subject groups were recruited: a) those who were treated with ECT as adolescents (n¼13); b) treated with ECT as adults (n¼25); c) hospitalized as adolescents but not treated with ECT (n¼30); and d) hospitalized as adults but not treated with ECT (n¼30). All subjects were interviewed using similar questions related to their satisfaction regarding different treatment modalities, including psychotherapy, pharmacotherapy, hospitalization and ECT. Results: Both adults and adolescents viewed ECT as a legitimate and an effective form of treatment (70%). Patients that were treated with ECT had a more positive attitude toward this treatment. In comparison to other treatment modalities, ECT was considered by both age groups as the least effective form of therapy. Adults were less satisfied with the quality of explanation received about ECT, whereas adolescents reported receiving more explanations from providers (e.g., physicians, nurses, parents). Conclusion: In order to effectively evaluate patient views about ECT, it is necessary to use a framework of informed. Keywords: Adolescent, ECT, patients' views, informed consent [0326] PHASE-SYNCHRONIZED TACS-INDUCED OSCILLATORY MODULATES CORTICO-CORTICAL SIGNALING EFFICACY
ACTIVITY
r*, Y. Morishima. 1 University Hospital of Psychiatry, Switzerland; K.D. Fehe PRESTO, Japan
2
Introduction: Synchronized brain oscillations are considered a basis for inter-regional neuronal communication [1,2]. However, the causal role of inter-regional oscillatory phase-synchrony in modulating cortico-cortical signaling efficacy has so far not been directly demonstrated. Methods: To address this relationship, we employed the simultaneous use of transcranial alternating current stimulation (tACS), TMS and EEG. Through tACS we introduced theta oscillatory activity in two regions of the human frontoparietal network; the dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex (PPC). We applied 6 Hz tACS to the DLPFC and PPC simultaneously in an in-phase or anti-phase manner. For assessing resultant changes in transmission in the frontoparietal network, we simultaneously applied weak single-pulse TMS over the DLPFC at four different phases of tACS (90 , 180 , 270 , 360 ) and measured the spread of TMS-evoked EEG potentials (TEPs). The amount of current spread is modulated by the functional status of the neural network, thereby providing a measure of changes in signaling efficacy [3]. Results: We found that the amplitude of TEPs depended on the phase of the introduced 6 Hz activity during in-phase and anti-phase tACS. These phasedependent changes of TEPs quickly propagated from the DLPFC to occipital areas in the in-phase condition. However, in the anti-phase condition, phase-dependent changes in TEPs did not reach occipital areas before 100 ms after the TMS, suggesting that the tACS-induced de-synchronization of the frontoparietal network limited communication in the network. Discussion: We demonstrate that a tACS-induced state of phase-synchrony across the frontoparietal network modulates signaling efficacy in the network, with anti-phase tACS efficiently limiting signal-propagation in the network. This supports the causal role of phase-synchronized endogenous oscillatory activity in modulating inter-regional neuronal communication, in accordance with the proposed communication-through-coherence model [1]. Keywords: Transcranial Alternating Current Stimulation, Transcranial Magnetic Stimulation, Electroencephalography, Functional connectivity References [1] Engel (2001). Nat Rev Neurosci. ki (2004). Science. [2] Buzsa [3] Ilmoniemi (1997). Neuroreport. [0329] EFFECTS OF TRANSCRANIAL STATIC MAGNETIC FIELD STIMULATION (TSMS) OF THE VISUAL CORTEX ON EXPERIMENTAL PHOTOPHOBIA n*1, E. Lozano-Soto 1, S. Sabbarese 1, B.A. Strange 2, G. V. Soto-Leo 1 ejicos, Spain; Foffani , A. Oliviero 1. 1 Hospital Nacional de Parapl 2 Universidad Politecnica de Madrid, Spain