- Email: [email protected]
P26-T Coil orientation matters: TMS-EEG to optimise the activation of pre-Supplementary motor area
e46
Abstracts / Clinical Neurophysiology 130 (2019) e21–e116
P26-T Coil orientation matters: TMS-EEG to optimise the activation of pre-Supplementary motor area—Lorenzo Rocchi a,b,*, Jaime Ibanez Pereda a, Alberto Benussi c, Vishal Rawji a, Sara Tremblay c, Elias Casula d, John Rothwell a (a Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, b Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy, c Royal Ottawa Institute of Mental Health Research, Ottawa, Canada, d Non-invasive Brain Stimulation Unit, IRCCS Santa Lucia Foundation, Roma, Italy) ⇑
Corresponding author.
Background: Studies using Transcranial Magnetic Stimulation (TMS) have demonstrated the possibility to target different neuronal populations within the primary motor cortex (M1) by changing coil orientation and stimulation intensity. The absence of a direct electrophysiological response such as motor evoked potentials has limited this investigation in areas outside M1. This problem can be solved with the use of combined TMS and electroencephalography, which allows direct recording of cortical responses to TMS pulses. Materials and methods: In this work on healthy human subjects we compared early (10–70 ms) and late (70–250 ms) transcranial evoked potentials (TEP) and TMS-related spectral perturbation (TRSP) obtained by delivering magnetic pulses over the pre-SMA with variable coil orientation (0°; 90°; 180° and 270°) and stimulation intensity (100%, 120% and 140% of resting motor threshold). Results: both early and late TEP were generally larger when the coil handle was pointing backwards (0[o). This result was true also for early TRSP but, surprisingly, late TRSP was greater when the coil was pointing at 180°. Additionally, stimulating the pre-SMA with a 90° orientation activated the right M1, thus limiting the spatial specificity of the stimulation. Conclusions: these results suggest that parameters such as coil orientation and stimulation intensity are critical when stimulating the pre-SMA and they should be taken into account in physiological and clinical studies. doi:10.1016/j.clinph.2019.04.389
P27-T Common pattern of information transfer in the brain for different modalities during a reasoning task—Maciej Kaminski a,*, Aneta Brzezicka b, Jan Kaminski c,d, Katarzyna Blinowska a,e (a University of Warsaw, Department of Biomedical Physics, Warsaw, Poland, b Faculty of Psychology, SWPS University of Social Sciences and Humanities, Warsaw, Poland, c Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, USA, d Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, USA, e Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland) ⇑
Corresponding author.
Background: Information processing in the brain involves the synchronization of brain structures realized by the transmission of rhythmic activity. The aim of our work was to find connectivity patterns between brain structures during the same mental activity performed during tasks with different stimuli modality. Material and methods: The task: the paradigm of linear syllogism was performed with visual (12 subjects) and auditory stimuli (29 subjects). The EEG activity transmission was analyzed by means of the short-time Directed Transfer Function (sDTF), a frequency
dependent estimator of directed coupling between time series based on the Granger causality principle. Results and conclusions: The obtained patterns showed similar coupling for both modalities involving EEG propagation mainly between the frontal and posterior areas which communicated intermittently. Our results indicate that the fronto-parietal network operated mainly in the theta frequency range as well as in other frequency ranges, especially gamma. By means of the assortative mixing approach, the strengths of coupling between the regions of interests (ROIs) were determined. For both modalities, the results showed stronger coupling within the ROIs than between them in agreement with the theories considering information transfer efficiency and metabolic energy savings. The patterns differences were minor and concerned stronger propagation from the posterior electrodes towards the frontal ones during the visual task and from the temporal sites to the frontal ones during the auditory task, which can be explained as bottom-up communication from specific sensory sites. Our results support a modality-free process of information retrieval and integration in a reasoning task. doi:10.1016/j.clinph.2019.04.390
P28-T Temporary changes of resting-state functional networks after fear learning—Kirill Efimov a,b,*, Olga Martynova a,c, Alina Tetereva a,c, Sergey Kartashov d, Alexey Ivanitsky a (a Institute of Higher Nervous activity and Neurophysiology, Russian Academy of Science, Moscow, Russian Federation, b Moscow Institute of Physics and Technology, Moscow, Russian Federation , c National Research University Higher School of Economics, Russian Federation, d National Research Center Kurchatov Institute, Russian Federation) ⇑
Corresponding author.
Introduction: Resting-state functional connectivity (rsFC) may indicate abnormalities in the brain physiology as it was shown at the example of altered rsFC within fear-processing brain circuit in patients with posttraumatic stress disorder. However, little is known about whether resting state networks vary their functional connections after experimental fear learning (FL). Here, we studied brain network changes in the resting state immediately, in one day and a week after FL using graph theory metrics. Methods: We collected resting state fMRI data from 19 healthy controls and 24 healthy participants of FL protocol. Control group underwent three fMRI sessions: the second and the third sessions took place in one day and a week after the first respectively. FL group underwent five sessions: before FL, with fear memory retrieval, after FL, one day after, and a week after the first. We calculated paired FC of 94 anatomical regions of interest and analyze graph theory metrics of reconstructed networks for each session. Results: The network during fear memory retrieval showed greater global efficiency than other resting state networks. Bilateral middle frontal gyri and parietal lobes became and remained network hubs after FL as well as in one day and one week afterward. No significant network changes were observed in the control group. Discussion and conclusions: Our findings highlight the temporary effect of FL at resting state networks, which implies the functional readjustment of neural connections even after mild aversive exposure. This study was funded by the Grant No. 16-15-00300 of the Russian Scientific Foundation. doi:10.1016/j.clinph.2019.04.391
Abstracts / Clinical Neurophysiology 130 (2019) e21–e116
P26-T Coil orientation matters: TMS-EEG to optimise the activation of pre-Supplementary motor area—Lorenzo Rocchi a,b,*, Jaime Ibanez Pereda a, Alberto Benussi c, Vishal Rawji a, Sara Tremblay c, Elias Casula d, John Rothwell a (a Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, b Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy, c Royal Ottawa Institute of Mental Health Research, Ottawa, Canada, d Non-invasive Brain Stimulation Unit, IRCCS Santa Lucia Foundation, Roma, Italy) ⇑
Corresponding author.
Background: Studies using Transcranial Magnetic Stimulation (TMS) have demonstrated the possibility to target different neuronal populations within the primary motor cortex (M1) by changing coil orientation and stimulation intensity. The absence of a direct electrophysiological response such as motor evoked potentials has limited this investigation in areas outside M1. This problem can be solved with the use of combined TMS and electroencephalography, which allows direct recording of cortical responses to TMS pulses. Materials and methods: In this work on healthy human subjects we compared early (10–70 ms) and late (70–250 ms) transcranial evoked potentials (TEP) and TMS-related spectral perturbation (TRSP) obtained by delivering magnetic pulses over the pre-SMA with variable coil orientation (0°; 90°; 180° and 270°) and stimulation intensity (100%, 120% and 140% of resting motor threshold). Results: both early and late TEP were generally larger when the coil handle was pointing backwards (0[o). This result was true also for early TRSP but, surprisingly, late TRSP was greater when the coil was pointing at 180°. Additionally, stimulating the pre-SMA with a 90° orientation activated the right M1, thus limiting the spatial specificity of the stimulation. Conclusions: these results suggest that parameters such as coil orientation and stimulation intensity are critical when stimulating the pre-SMA and they should be taken into account in physiological and clinical studies. doi:10.1016/j.clinph.2019.04.389
P27-T Common pattern of information transfer in the brain for different modalities during a reasoning task—Maciej Kaminski a,*, Aneta Brzezicka b, Jan Kaminski c,d, Katarzyna Blinowska a,e (a University of Warsaw, Department of Biomedical Physics, Warsaw, Poland, b Faculty of Psychology, SWPS University of Social Sciences and Humanities, Warsaw, Poland, c Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, USA, d Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, USA, e Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland) ⇑
Corresponding author.
Background: Information processing in the brain involves the synchronization of brain structures realized by the transmission of rhythmic activity. The aim of our work was to find connectivity patterns between brain structures during the same mental activity performed during tasks with different stimuli modality. Material and methods: The task: the paradigm of linear syllogism was performed with visual (12 subjects) and auditory stimuli (29 subjects). The EEG activity transmission was analyzed by means of the short-time Directed Transfer Function (sDTF), a frequency
dependent estimator of directed coupling between time series based on the Granger causality principle. Results and conclusions: The obtained patterns showed similar coupling for both modalities involving EEG propagation mainly between the frontal and posterior areas which communicated intermittently. Our results indicate that the fronto-parietal network operated mainly in the theta frequency range as well as in other frequency ranges, especially gamma. By means of the assortative mixing approach, the strengths of coupling between the regions of interests (ROIs) were determined. For both modalities, the results showed stronger coupling within the ROIs than between them in agreement with the theories considering information transfer efficiency and metabolic energy savings. The patterns differences were minor and concerned stronger propagation from the posterior electrodes towards the frontal ones during the visual task and from the temporal sites to the frontal ones during the auditory task, which can be explained as bottom-up communication from specific sensory sites. Our results support a modality-free process of information retrieval and integration in a reasoning task. doi:10.1016/j.clinph.2019.04.390
P28-T Temporary changes of resting-state functional networks after fear learning—Kirill Efimov a,b,*, Olga Martynova a,c, Alina Tetereva a,c, Sergey Kartashov d, Alexey Ivanitsky a (a Institute of Higher Nervous activity and Neurophysiology, Russian Academy of Science, Moscow, Russian Federation, b Moscow Institute of Physics and Technology, Moscow, Russian Federation , c National Research University Higher School of Economics, Russian Federation, d National Research Center Kurchatov Institute, Russian Federation) ⇑
Corresponding author.
Introduction: Resting-state functional connectivity (rsFC) may indicate abnormalities in the brain physiology as it was shown at the example of altered rsFC within fear-processing brain circuit in patients with posttraumatic stress disorder. However, little is known about whether resting state networks vary their functional connections after experimental fear learning (FL). Here, we studied brain network changes in the resting state immediately, in one day and a week after FL using graph theory metrics. Methods: We collected resting state fMRI data from 19 healthy controls and 24 healthy participants of FL protocol. Control group underwent three fMRI sessions: the second and the third sessions took place in one day and a week after the first respectively. FL group underwent five sessions: before FL, with fear memory retrieval, after FL, one day after, and a week after the first. We calculated paired FC of 94 anatomical regions of interest and analyze graph theory metrics of reconstructed networks for each session. Results: The network during fear memory retrieval showed greater global efficiency than other resting state networks. Bilateral middle frontal gyri and parietal lobes became and remained network hubs after FL as well as in one day and one week afterward. No significant network changes were observed in the control group. Discussion and conclusions: Our findings highlight the temporary effect of FL at resting state networks, which implies the functional readjustment of neural connections even after mild aversive exposure. This study was funded by the Grant No. 16-15-00300 of the Russian Scientific Foundation. doi:10.1016/j.clinph.2019.04.391