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Abstracts / Brain Stimulation 8 (2015) 360e377
pulse TMS over the right superior cerebellum (lobule 6) [3] and verified the necessity of the left superior (with visual and motor control) and inferior cerebellum during visual working memory with a double-pulse (1s interval) stimulation using fMRI-guided TMS [4]. In the current follow-up study, involvement of the right inferior cerebellum during visual working memory is further investigated. Methods: 9 healthy, right-handed young-adults performed 2 tasks: (1) Visual Memory TMS (VM-TMS) and (2) Verbal Memory TMS (VERM-TMS) while a double-pulse (1s interval) stimulation sequence was applied over the right inferior cerebellum (lobule 8A/ 7B) specific to VM activation during fMRI-guided (BrainSight Ver2) TMS (Magstim Rapid2 system with a 110mm double cone coil). Each task comprised of two runs of 18 stimulation (Stim) and 18 nonstimulation (non-Stim) trials per run (Fig. 1). Task order was counterbalanced across all subjects.
7B and not 8, hence disrupting the visual processes essential for VM but not VERM. Further investigations using VERM fMRIguided targets in the right inferior cerebellum are needed to ascertain this. References 1. Stoodley CJ , Schmahmann JD . Functional topography in the human cerebellum: a meta- analysis of neuroimaging studies. NeuroImage 2009;44(2): 489e501. 2. E, K.H , et al. A meta-analysis of cerebellar contributions to higher cognition from PET and fMRI studies. Human brain mapping 2014;35(2):593e615. 3. Desmond JE , Chen SH , Shieh PB . Cerebellar transcranial magnetic stimulation impairs verbal working memory. Annals of Neurology 2005;58(4): 553e60. 4. Chen SHA , et al. Cerebellar transcranial magnetic simulation (TMS) impairs visual working memory in 20th Annual Human Brain Mapping. Hamburg: Germany; 2014. 5. Kirschen PK , Chen SHA , Desmond JE . Modality specific cerebro-cerebellar activations in verbal working memory: an fMRI study. Behav Neurol 2010;23(1-2): 51e63.
216 Effects of deep brain stimulation of the nucleus basalis of Meynert in EEG resting-state oscillatory power and phase synchronization H.L. Lee a,*, J. Kuhn b, K. Hardenacke b, T.O.J. Gruendler b,c,d, T. Schueller b, V. Sturm e, J. Fell f, N. Axmacher a,g a German Center for Neurodegenerative Diseases, Bonn, Germany b University of Cologne, Germany c Otto-von-Guericke University Magdeburg, Germany c Center for Behavioral Brain Sciences, Magdeburg, Germany e University of Wuerzburg, Germany f University of Bonn, Germany g Ruhr University Bochum, Germany *E-mail: [email protected].
Results: Paired t-tests showed, TMS administered to the right inferior cerebellum, decreased accuracy only in the VM-TMS task (t [8]¼4.64;p¼0.0017), but had no effects on RT or the VERM-TMS conditions (Fig. 2).
Discussion: Our findings verified the contributions of the right inferior cerebellum during VM-TMS and possible topographic specificity for visual and verbal WM within this lobule. Kirschen et al. [5] showed the right lobule 8 to be activated specifically for auditory input and lobule 7B for visual processes during VERM. It is plausible that our lack of significant effect during VERM-TMS is explained by the TMS target to be within lobule
Introduction: Deep brain stimulation (DBS) has been proposed to ameliorate memory dysfunction in patients with Alzheimer’s disease (AD). In this study, we investigated the changes in electroencephalography (EEG) resting-state oscillatory power and phase synchronization after one year of DBS of the nucleus basalis of Meynert (NBM) in AD patients. Methods: EEG resting-state data were recorded before and after one year of DBS of NBM in 7 AD patients. The data were segmented into epochs of 2s, and EEG epochs with ocular, muscular and other types of artifacts were discarded from subsequent analyses. Oscillatory power across trials of each electrode, and averaged pairwise phase consistency (PPC) across trials of each electrode paired with all other electrodes were compared before and after DBS in each frequency band of interests (delta: 24 Hz, theta: 4-8 Hz, alpha1: 8-10.5 Hz, alpha2: 10.5-13 Hz, beta1: 13-20 Hz, beta2: 20-30 Hz, gamma1: 30-40 Hz, and gamma2: 40-80 Hz). Results: As compared to before DBS, patients after DBS demonstrate increased oscillatory power in the delta (strongest), theta, beta2, and gamma1 frequency bands. Further, patients after DBS also demonstrate increased averaged PPC in the delta frequency band, and decreased averaged PPC in the alpha2, beta1, beta2, gamma1 and gamma2 frequency bands. Discussion: Our results demonstrate changes in EEG restingstate oscillatory power and phase synchronization for AD patients after one year of DBS of NBM. Changes in the beta and gamma frequency bands are often associated with memory functions, whereas changes in the delta and theta frequency bands are most likely related to progression of the disease. Further examination of the relationship between cognitive
Abstracts / Brain Stimulation 8 (2015) 360e377
neuropsychological testing and resting-state oscillatory power and phase synchronization will determine whether these EEG resting-state changes are associated with cognitive functioning in AD patients. 217 Beneficial effect of transcranic magnetic stimulation combined with mirror therapy in stroke patients: a pilot study in neurorehabilitative setting D. Dalla Libera , S. Regazzi , C. Fasoletti , D. Dinacci Ruggieri , P. Rossi Hildebrand, Neurorehabilitation, Brissago, Switzerland Introduction: Both mirror therapy (MT) and repetitive transcranial magnetic stimulation (TMS) have been proved to promote cortical reorganization and functional recovery of post- stroke patients. Methods: Ten patients affected by subacute first-ever stroke documented by a brain CT- with severe disability (NIHSS 10-14) and hand paresis were recruited at 3 months from the event and received a complete neurological examination including MRC, NIHSS, Brunnstrom Recovery Stages, Fugl-Meyer grading. Moreover, FAB, BECK, 10-item Spielberger Trait Anger Scale, Montreal Cognitive Assessment (MoCa) and FIM were recorded. They underwent 12 session (3 time/week) of 15 minutes of 10 Hz TMS through a 8-coil applied on the ipsilesional somatosensory cortex of the affected emisphere, followed by 15 minutes of MT for the upper limb. A control group of ten patients underwent TMS stimulation withouth MT. Double-pulse TMS through a figure-eight focal coil was used to study intracortical inhibition (ICI) in primary motor cortex of both side at rest and during the preparation of movement. Results: The first group (TMS + MT) shows better results than the second group (TMS only) both from a clinical and neurophysiological point of view. A motor evoked potentials - previously absent - was elicited after 1 month treatment for the affected upper limb; a normalization of the silent period and reduction of and intracortical inhibition in the affected emisphere was evident, together with a significant modification of ICI over the unaffected hemisphere. Such results were reproducible in 3 evaluations done on different time. Conclusion: TMS treatment combined with MT may be added to the conventional therapy of severely impaired stroke patients even in an early phase after the insult, with positive results on both neurophysiological and clinical parameters. We may suppose that TMS, when combined with MT enhances synaptic plasticity and induce nerugenesis. 218 Evaluation of tDCS-induced Cortical Excitability Changes by Motor Evoked Potentials Amplitude A.V. Masliukova , N.A. Smirnov Ivanovo State Medical Academy, Ivanovo, Russia Background: The present study investigated the possibility of assessment of excitatory anodal transcranial direct current stimulation (tDCS) and inhibitory cathodal tDCA to the motor cortex measured by the amplitude of the motor evoked potential (MEP) using navigated transcranial magnetic stimulation (TMS). Methods: Ten healthy right-handed adults received anodal and cathodal tDCS separated by at least 24 hours. The order of tDCS polarity conditions (anodal vs. cathodal) was counterbalanced among participants. TDCS was delivered through a couple of saline-soaked, sponge electrodes (30 cm2) using a constantcurrent stimulator built in Neuron-Spectrum-5 (Neurosoft) with an intensity of 2 mA for 20 min. The active electrode was placed
377
over the motor cortical representational field of the right abductor pollicis brevis (APB), defined by means of navigated TMS. “Neuro-MS/D” (Neurosoft) stimulator with Neural Navigator (“NeNa”, Brain Science Tools) guided by individual MRI data were used for navigated TMS. The reference electrode was placed over the right frontopolar cortex (above the eyebrow). However, in the present study, stimulation may have extended beyond field of the right APB due to the large electrode size used. Recording of MEPs from the APB was performed with NeuronSpectrum-5 (Neurosoft) before the tDCS (baseline) and immediately after. Results: The analyses showed that the MEP amplitudes increased +29.2 7.6% following the anodal stimulation (P < 0.01) and decreased -20.7 5.8% following the cathodal stimulation (P <0.05), compared with the baseline. Moreover, after tDCS, we found a significant difference in the mean MEP amplitudes between the two tDCS conditions (after anodal 381.5 mV and after cathodal 267.8 mV; p<0.001). Conclusions: The study revealed that anodal and cathodal tDCS are both techniques to induce cortical excitability changes. And it is possible to directly evaluate tDCS-induced changes at the cortical level by recording the MEPs using navigated TMS.
219 A TMS-EEG study for attentional gating by oscillatory alpha activity Yuka Okazaki a,*, Yuji Mizuno a,b,c, Keiichi Kitajo a,b a RIKEN Brain Science Institute, Japan b Tokyo University of Agriculture and Technology, Japan c Japan Society for the Promotion of Science, Japan *E-mail: [email protected]. Introduction: It is well accepted that alpha activity is hemispherically lateralized during orienting of attention associated with sensory gating. The underlying mechanism, however, has not been fully understood. We hypothesized that ongoing oscillations are more robust to phase perturbation under the higher alpha power state than the lower alpha power state reflecting the dynamics of neural oscillations, which is less sensitive to external inputs. To test this hypothesis, we assessed the extent to which phase of ongoing oscillations is modulated by the transcranial magnetic stimulation (TMS) under varying alpha power states in a covert attention-orienting task. Methods: A target Gabor stimulus was presented at a cued location in either the left or right visual hemifield, together with a distractor Gabor stimulus. The participants were asked to covertly attend to the cued hemifield and discriminate the orientation of the target stimulus. In half of the trials TMS was applied on the left or right visual hemisphere instead of a presentation of Gabor stimulus. We analysed brain responses to TMS-perturbation on the ipsilateral or contralateral hemispheres with respect to the attentional cueing. Results: Our key finding was that the lower alpha power related to the target led to strong phase resetting, while the higher alpha power related to the distracter resulted in weaker phase resetting. Moreover, the phase resetting propagated from the TMS-targeted visual area to the rest of the brain but the propagation was less efficient when pre-TMS alpha power was high. Discussion: Our results provide a new mechanistic account that oscillatory alpha dynamics plays an important role in sensory gating by modulating the alpha power together with the efficiency of global propagation of phase resetting. This alpha dynamics is presumably associated with information flow between task-relevant regions.
Abstracts / Brain Stimulation 8 (2015) 360e377
pulse TMS over the right superior cerebellum (lobule 6) [3] and verified the necessity of the left superior (with visual and motor control) and inferior cerebellum during visual working memory with a double-pulse (1s interval) stimulation using fMRI-guided TMS [4]. In the current follow-up study, involvement of the right inferior cerebellum during visual working memory is further investigated. Methods: 9 healthy, right-handed young-adults performed 2 tasks: (1) Visual Memory TMS (VM-TMS) and (2) Verbal Memory TMS (VERM-TMS) while a double-pulse (1s interval) stimulation sequence was applied over the right inferior cerebellum (lobule 8A/ 7B) specific to VM activation during fMRI-guided (BrainSight Ver2) TMS (Magstim Rapid2 system with a 110mm double cone coil). Each task comprised of two runs of 18 stimulation (Stim) and 18 nonstimulation (non-Stim) trials per run (Fig. 1). Task order was counterbalanced across all subjects.
7B and not 8, hence disrupting the visual processes essential for VM but not VERM. Further investigations using VERM fMRIguided targets in the right inferior cerebellum are needed to ascertain this. References 1. Stoodley CJ , Schmahmann JD . Functional topography in the human cerebellum: a meta- analysis of neuroimaging studies. NeuroImage 2009;44(2): 489e501. 2. E, K.H , et al. A meta-analysis of cerebellar contributions to higher cognition from PET and fMRI studies. Human brain mapping 2014;35(2):593e615. 3. Desmond JE , Chen SH , Shieh PB . Cerebellar transcranial magnetic stimulation impairs verbal working memory. Annals of Neurology 2005;58(4): 553e60. 4. Chen SHA , et al. Cerebellar transcranial magnetic simulation (TMS) impairs visual working memory in 20th Annual Human Brain Mapping. Hamburg: Germany; 2014. 5. Kirschen PK , Chen SHA , Desmond JE . Modality specific cerebro-cerebellar activations in verbal working memory: an fMRI study. Behav Neurol 2010;23(1-2): 51e63.
216 Effects of deep brain stimulation of the nucleus basalis of Meynert in EEG resting-state oscillatory power and phase synchronization H.L. Lee a,*, J. Kuhn b, K. Hardenacke b, T.O.J. Gruendler b,c,d, T. Schueller b, V. Sturm e, J. Fell f, N. Axmacher a,g a German Center for Neurodegenerative Diseases, Bonn, Germany b University of Cologne, Germany c Otto-von-Guericke University Magdeburg, Germany c Center for Behavioral Brain Sciences, Magdeburg, Germany e University of Wuerzburg, Germany f University of Bonn, Germany g Ruhr University Bochum, Germany *E-mail: [email protected].
Results: Paired t-tests showed, TMS administered to the right inferior cerebellum, decreased accuracy only in the VM-TMS task (t [8]¼4.64;p¼0.0017), but had no effects on RT or the VERM-TMS conditions (Fig. 2).
Discussion: Our findings verified the contributions of the right inferior cerebellum during VM-TMS and possible topographic specificity for visual and verbal WM within this lobule. Kirschen et al. [5] showed the right lobule 8 to be activated specifically for auditory input and lobule 7B for visual processes during VERM. It is plausible that our lack of significant effect during VERM-TMS is explained by the TMS target to be within lobule
Introduction: Deep brain stimulation (DBS) has been proposed to ameliorate memory dysfunction in patients with Alzheimer’s disease (AD). In this study, we investigated the changes in electroencephalography (EEG) resting-state oscillatory power and phase synchronization after one year of DBS of the nucleus basalis of Meynert (NBM) in AD patients. Methods: EEG resting-state data were recorded before and after one year of DBS of NBM in 7 AD patients. The data were segmented into epochs of 2s, and EEG epochs with ocular, muscular and other types of artifacts were discarded from subsequent analyses. Oscillatory power across trials of each electrode, and averaged pairwise phase consistency (PPC) across trials of each electrode paired with all other electrodes were compared before and after DBS in each frequency band of interests (delta: 24 Hz, theta: 4-8 Hz, alpha1: 8-10.5 Hz, alpha2: 10.5-13 Hz, beta1: 13-20 Hz, beta2: 20-30 Hz, gamma1: 30-40 Hz, and gamma2: 40-80 Hz). Results: As compared to before DBS, patients after DBS demonstrate increased oscillatory power in the delta (strongest), theta, beta2, and gamma1 frequency bands. Further, patients after DBS also demonstrate increased averaged PPC in the delta frequency band, and decreased averaged PPC in the alpha2, beta1, beta2, gamma1 and gamma2 frequency bands. Discussion: Our results demonstrate changes in EEG restingstate oscillatory power and phase synchronization for AD patients after one year of DBS of NBM. Changes in the beta and gamma frequency bands are often associated with memory functions, whereas changes in the delta and theta frequency bands are most likely related to progression of the disease. Further examination of the relationship between cognitive
Abstracts / Brain Stimulation 8 (2015) 360e377
neuropsychological testing and resting-state oscillatory power and phase synchronization will determine whether these EEG resting-state changes are associated with cognitive functioning in AD patients. 217 Beneficial effect of transcranic magnetic stimulation combined with mirror therapy in stroke patients: a pilot study in neurorehabilitative setting D. Dalla Libera , S. Regazzi , C. Fasoletti , D. Dinacci Ruggieri , P. Rossi Hildebrand, Neurorehabilitation, Brissago, Switzerland Introduction: Both mirror therapy (MT) and repetitive transcranial magnetic stimulation (TMS) have been proved to promote cortical reorganization and functional recovery of post- stroke patients. Methods: Ten patients affected by subacute first-ever stroke documented by a brain CT- with severe disability (NIHSS 10-14) and hand paresis were recruited at 3 months from the event and received a complete neurological examination including MRC, NIHSS, Brunnstrom Recovery Stages, Fugl-Meyer grading. Moreover, FAB, BECK, 10-item Spielberger Trait Anger Scale, Montreal Cognitive Assessment (MoCa) and FIM were recorded. They underwent 12 session (3 time/week) of 15 minutes of 10 Hz TMS through a 8-coil applied on the ipsilesional somatosensory cortex of the affected emisphere, followed by 15 minutes of MT for the upper limb. A control group of ten patients underwent TMS stimulation withouth MT. Double-pulse TMS through a figure-eight focal coil was used to study intracortical inhibition (ICI) in primary motor cortex of both side at rest and during the preparation of movement. Results: The first group (TMS + MT) shows better results than the second group (TMS only) both from a clinical and neurophysiological point of view. A motor evoked potentials - previously absent - was elicited after 1 month treatment for the affected upper limb; a normalization of the silent period and reduction of and intracortical inhibition in the affected emisphere was evident, together with a significant modification of ICI over the unaffected hemisphere. Such results were reproducible in 3 evaluations done on different time. Conclusion: TMS treatment combined with MT may be added to the conventional therapy of severely impaired stroke patients even in an early phase after the insult, with positive results on both neurophysiological and clinical parameters. We may suppose that TMS, when combined with MT enhances synaptic plasticity and induce nerugenesis. 218 Evaluation of tDCS-induced Cortical Excitability Changes by Motor Evoked Potentials Amplitude A.V. Masliukova , N.A. Smirnov Ivanovo State Medical Academy, Ivanovo, Russia Background: The present study investigated the possibility of assessment of excitatory anodal transcranial direct current stimulation (tDCS) and inhibitory cathodal tDCA to the motor cortex measured by the amplitude of the motor evoked potential (MEP) using navigated transcranial magnetic stimulation (TMS). Methods: Ten healthy right-handed adults received anodal and cathodal tDCS separated by at least 24 hours. The order of tDCS polarity conditions (anodal vs. cathodal) was counterbalanced among participants. TDCS was delivered through a couple of saline-soaked, sponge electrodes (30 cm2) using a constantcurrent stimulator built in Neuron-Spectrum-5 (Neurosoft) with an intensity of 2 mA for 20 min. The active electrode was placed
377
over the motor cortical representational field of the right abductor pollicis brevis (APB), defined by means of navigated TMS. “Neuro-MS/D” (Neurosoft) stimulator with Neural Navigator (“NeNa”, Brain Science Tools) guided by individual MRI data were used for navigated TMS. The reference electrode was placed over the right frontopolar cortex (above the eyebrow). However, in the present study, stimulation may have extended beyond field of the right APB due to the large electrode size used. Recording of MEPs from the APB was performed with NeuronSpectrum-5 (Neurosoft) before the tDCS (baseline) and immediately after. Results: The analyses showed that the MEP amplitudes increased +29.2 7.6% following the anodal stimulation (P < 0.01) and decreased -20.7 5.8% following the cathodal stimulation (P <0.05), compared with the baseline. Moreover, after tDCS, we found a significant difference in the mean MEP amplitudes between the two tDCS conditions (after anodal 381.5 mV and after cathodal 267.8 mV; p<0.001). Conclusions: The study revealed that anodal and cathodal tDCS are both techniques to induce cortical excitability changes. And it is possible to directly evaluate tDCS-induced changes at the cortical level by recording the MEPs using navigated TMS.
219 A TMS-EEG study for attentional gating by oscillatory alpha activity Yuka Okazaki a,*, Yuji Mizuno a,b,c, Keiichi Kitajo a,b a RIKEN Brain Science Institute, Japan b Tokyo University of Agriculture and Technology, Japan c Japan Society for the Promotion of Science, Japan *E-mail: [email protected]. Introduction: It is well accepted that alpha activity is hemispherically lateralized during orienting of attention associated with sensory gating. The underlying mechanism, however, has not been fully understood. We hypothesized that ongoing oscillations are more robust to phase perturbation under the higher alpha power state than the lower alpha power state reflecting the dynamics of neural oscillations, which is less sensitive to external inputs. To test this hypothesis, we assessed the extent to which phase of ongoing oscillations is modulated by the transcranial magnetic stimulation (TMS) under varying alpha power states in a covert attention-orienting task. Methods: A target Gabor stimulus was presented at a cued location in either the left or right visual hemifield, together with a distractor Gabor stimulus. The participants were asked to covertly attend to the cued hemifield and discriminate the orientation of the target stimulus. In half of the trials TMS was applied on the left or right visual hemisphere instead of a presentation of Gabor stimulus. We analysed brain responses to TMS-perturbation on the ipsilateral or contralateral hemispheres with respect to the attentional cueing. Results: Our key finding was that the lower alpha power related to the target led to strong phase resetting, while the higher alpha power related to the distracter resulted in weaker phase resetting. Moreover, the phase resetting propagated from the TMS-targeted visual area to the rest of the brain but the propagation was less efficient when pre-TMS alpha power was high. Discussion: Our results provide a new mechanistic account that oscillatory alpha dynamics plays an important role in sensory gating by modulating the alpha power together with the efficiency of global propagation of phase resetting. This alpha dynamics is presumably associated with information flow between task-relevant regions.