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P277: The role of the cerebellum on motor imagery
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Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
method is optimal for detecting cTBS-induced after-effects. Therefore, we constructed input-output curves before and following cTBS to determine the range of test intensities that are most sensitive to the effects of cTBS. Methods: Single-pulse TMS was applied to the left motor cortex and MEPs were recorded from the right first dorsal interosseous muscle. To construct input-output curves, eight TMS pulses were applied at ten different stimulus intensities between 90% and 180% of resting motor threshold (RMT) in a pseudo-randomised order. Curves were measured five times: twice at baseline and at 0, 15, and 30 min following cTBS. Results: There was no effect of cTBS on MEPs evoked using near-threshold stimulus intensities, nor was there a change in MEPs at intermediate stimulus intensities above threshold. However, MEPs evoked using intensities between 150% and 180% RMT (corresponding to the upper end of the sigmoidal input-output curve) were depressed following cTBS. Conclusions: These results suggest that test intensities higher than those conventionally used may be required to detect cTBS-induced changes in corticospinal excitability.
P273 Fast induction of alpha entrainment with bandwidth confined electric and photic stimulation S. Schmidt 1 , M. Scholz 2 , L. Haberbosch 1 , A. Mante 1 , K. Obermayer 2 , S.A. Brandt 1 1 Charité-Universitaetsmedizin Berlin, Vision & Motor Research Group, Dept. Neurology, Berlin, Germany; 2 Technical University Berlin, Neural Information Processing Group, Berlin, Germany Introduction: Brain stimulation is emerging as a fundamental tool in the clinical repertoire of a neurologist. Whereas invasive approaches are well established in clinical practice, non-invasive approaches are quickly gaining on importance. Independent of the type of stimulation, it is becoming remarkably clear that a better understanding of the neurophysiological mechanisms of interactions between patterns of stimulation and patterns of subject specific neural activity is necessary. The aim of this pilot study is to address if short periods of stimulation can entrain brain-rhythms. More explicitly, due to striking neurophysiological similarities between “photic driving” and “transorbital alternating current stimulation”, we compare short term photic- and electric stimulation. The hypothesis is that 30 seconds of bandwidth confined stimulation will evoke entrainment of the central alpha rhythm. Methods: To address this question, we stimulated 10 healthy subjects with retinofugal alternating current stimulation at 10 Hz for 30 seconds. In direct comparison, we induced steady-state visual evoked potentials at 10 Hz for 30 seconds. Sessions were applied in randomized order with baseline EEG recordings prior, during and after stimulation. EEG analyses were defined by clinical standards to identify “photic driving”. Results: In this framework we investigated: if a subject was susceptible to 10 Hz photic stimulation (DRIVING), if carry over effects exist for visual (VIS POST) and electric (ELC POST) stimulation. Results show that entrainment (DRIVING) could be induced and that alpha-entrainment persisted in both VIS POST and ELC POST conditions. All effects were significant in one-sided paired t-tests against baseline (p<0.05). Discussion: These findings show that short terms of brief stimulation can evoke significant entrainment of central rhythms. Remarkably, this was the case for both electric and photic stimulation. This provides a method to investigate quick changes in central rhythms induced by stimulation. One perspective is Brain-Computer-Interface driven stimulus optimization (DFG grant Nr: BR 1691/8-1).
P274 Influence of slow oscillating transcranial direct current stimulation (so-tDCS) on sleep EEG with focus on spindle density and cognitive performance on healthy subjects C. Garcia, N. Nadi, R. Weise, I. von Mengden, M. Glos, T. Penzel Charité, Sleep Medicine, Berlin, Germany Introduction: Previous experiments with transcranial direct current stimulation before sleep on healthy subjects showed a tendency towards an increased spindle density during sleep. So we performed a randomized, sham-controlled and double-blinded study on 10 male subjects between 20-30 years. Methods: We stimulated subjects with a frequency of 0.2 Hz and a si-
nusoidal waveform with a current of 550 μA and a DC offset of 275 μA. Stimulation electrodes were placed bilaterally on C3, C4, left and right mastoids. We stimulated 30min with a 1min free interval after every 5 minutes in the evening before subjects underwent polysomnography. Before and after the night in the sleep laboratory subjects had to perform several tests. Results: Final results according spindle density are still outstanding. Visual spindle counting leads to a high intra- and interratervariability. Therefore we needed to establish a reliable counting method first. We found no significant difference in cognitive performance or sleep stage distribution. But subjects reported more sleepiness after a night with evening stimulation.
P277 The role of the cerebellum on motor imagery B. Cengiz, E. Boran Gazi University Faculty of Medicine, Neurology, Ankara, Turkey Introduction: It’s thought that the cerebellum plays a role in motor imagery (MI). Although there are some neuroimaging evidences support this, limited number of data investigated the role of the cerebellum on MI, in terms of neurophysiology. The aim of the this study is to explore the role of the cerebellum on MI. Cerebellar transcranial direct current stimulation (ctDCS) was used to modulate cerebellar excitability. Method: 11 healthy subjects were recruited the study (3 female, aged between 27-47, mean 33.3±8. 7). Subjects were instructed to image two different motor task. Abduction of the index finger was the simple task, while tell one’s beads was the complex one. MEPs were elicited from right first dorsal interosseous muscle. The basal MEP amplitude was calculated average values of 30 MEPs. The effect of MI on motor cortical excitability was measured by MEPs amplitude changes. Resting motor threshold (rMT), threshold for 1 mV motor evoked potential (MEP) and silent period (SP) were measured before and after ctDCS. Each subject underwent two different cerebellar modulation study: anodal stimulation and sham stimulation. The interval between experiments was at least one week. tDCS was delivered through two sponge embedded in a saline-soaked solution. Active electrode was centered on the right cerebellar cortex, 3 cm lateral to the inion. Reference electrode was positioned on the right masseter muscle. The intensity of stimulation was set at 2 mA for 20 min. Sham cTDCS consists of 30 seconds current stimulation. Results: Anodal ctDCS: • Before ctDCS: basal MEP values: 976.4±425. μV, after simple MI: 1858.2±743.7 μV (p=0.000), after complex MI: 1014.2±724. 8 μV (p>0.05). • After ctDCS: basal MEP values: 952.4±719.2 μV, after simple MI: 1202.9±376.4 μV (p>0.05), after comple.x MI: 934.8±724. 8 μV (p>0.05). Sham ctDCS: • Before ctDCS: basal MEP values: 1102.6±290.5 μV, after simple MI: 1970.2±989.9 μV (p=0.009), after complex MI: 1446.9±615.3 μV p=0.0016). • After ctDCS: basal MEP values: 1090.1±339.6 μV, after simple MI: 1857.5.9±930.2 μV (p=0, 016), after complex MI: 1421.7±785. 8 μV (p=0. 001). Conclusion: The results of the study indicate that the cerebellum modulates MI. The finding that suppression of MEP amplitude increase during MI with anodal ctDCS indicates that it has an inhibitory effect on MI.
P278 Facilitatory effects in a perceptual learning task through an “inhibitory” stimulation A. Fertonani 1 , C. Pirulli 1 , C. Miniussi 1,2 1 IRCCS Centro S. Giovanni di Dio - Fatebenefratelli, Cognitive Neuroscience Section, Brescia, Italy; 2 University of Brescia, Clinical and Experimental Sciences, Brescia, Italy Question: In the cognitive neuroscience domain no clear correlation emerges between transcranial direct current stimulation polarity (anodal a-tDCS vs. cathodal c-tDCS), and behavioural performance (improvement vs. impairment). Contradictory results are present mainly for c-tDCS. Therefore our aim was to investigate if and how some variables i.e., c-tDCS timing, pauses during c-tDCS and duration of c-tDCS affect performance, in the healthy adult brain. We applied c-tDCS before or during a task execution (before vs. during - timing), continuous vs. paused c-tDCS (yes vs. no
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
method is optimal for detecting cTBS-induced after-effects. Therefore, we constructed input-output curves before and following cTBS to determine the range of test intensities that are most sensitive to the effects of cTBS. Methods: Single-pulse TMS was applied to the left motor cortex and MEPs were recorded from the right first dorsal interosseous muscle. To construct input-output curves, eight TMS pulses were applied at ten different stimulus intensities between 90% and 180% of resting motor threshold (RMT) in a pseudo-randomised order. Curves were measured five times: twice at baseline and at 0, 15, and 30 min following cTBS. Results: There was no effect of cTBS on MEPs evoked using near-threshold stimulus intensities, nor was there a change in MEPs at intermediate stimulus intensities above threshold. However, MEPs evoked using intensities between 150% and 180% RMT (corresponding to the upper end of the sigmoidal input-output curve) were depressed following cTBS. Conclusions: These results suggest that test intensities higher than those conventionally used may be required to detect cTBS-induced changes in corticospinal excitability.
P273 Fast induction of alpha entrainment with bandwidth confined electric and photic stimulation S. Schmidt 1 , M. Scholz 2 , L. Haberbosch 1 , A. Mante 1 , K. Obermayer 2 , S.A. Brandt 1 1 Charité-Universitaetsmedizin Berlin, Vision & Motor Research Group, Dept. Neurology, Berlin, Germany; 2 Technical University Berlin, Neural Information Processing Group, Berlin, Germany Introduction: Brain stimulation is emerging as a fundamental tool in the clinical repertoire of a neurologist. Whereas invasive approaches are well established in clinical practice, non-invasive approaches are quickly gaining on importance. Independent of the type of stimulation, it is becoming remarkably clear that a better understanding of the neurophysiological mechanisms of interactions between patterns of stimulation and patterns of subject specific neural activity is necessary. The aim of this pilot study is to address if short periods of stimulation can entrain brain-rhythms. More explicitly, due to striking neurophysiological similarities between “photic driving” and “transorbital alternating current stimulation”, we compare short term photic- and electric stimulation. The hypothesis is that 30 seconds of bandwidth confined stimulation will evoke entrainment of the central alpha rhythm. Methods: To address this question, we stimulated 10 healthy subjects with retinofugal alternating current stimulation at 10 Hz for 30 seconds. In direct comparison, we induced steady-state visual evoked potentials at 10 Hz for 30 seconds. Sessions were applied in randomized order with baseline EEG recordings prior, during and after stimulation. EEG analyses were defined by clinical standards to identify “photic driving”. Results: In this framework we investigated: if a subject was susceptible to 10 Hz photic stimulation (DRIVING), if carry over effects exist for visual (VIS POST) and electric (ELC POST) stimulation. Results show that entrainment (DRIVING) could be induced and that alpha-entrainment persisted in both VIS POST and ELC POST conditions. All effects were significant in one-sided paired t-tests against baseline (p<0.05). Discussion: These findings show that short terms of brief stimulation can evoke significant entrainment of central rhythms. Remarkably, this was the case for both electric and photic stimulation. This provides a method to investigate quick changes in central rhythms induced by stimulation. One perspective is Brain-Computer-Interface driven stimulus optimization (DFG grant Nr: BR 1691/8-1).
P274 Influence of slow oscillating transcranial direct current stimulation (so-tDCS) on sleep EEG with focus on spindle density and cognitive performance on healthy subjects C. Garcia, N. Nadi, R. Weise, I. von Mengden, M. Glos, T. Penzel Charité, Sleep Medicine, Berlin, Germany Introduction: Previous experiments with transcranial direct current stimulation before sleep on healthy subjects showed a tendency towards an increased spindle density during sleep. So we performed a randomized, sham-controlled and double-blinded study on 10 male subjects between 20-30 years. Methods: We stimulated subjects with a frequency of 0.2 Hz and a si-
nusoidal waveform with a current of 550 μA and a DC offset of 275 μA. Stimulation electrodes were placed bilaterally on C3, C4, left and right mastoids. We stimulated 30min with a 1min free interval after every 5 minutes in the evening before subjects underwent polysomnography. Before and after the night in the sleep laboratory subjects had to perform several tests. Results: Final results according spindle density are still outstanding. Visual spindle counting leads to a high intra- and interratervariability. Therefore we needed to establish a reliable counting method first. We found no significant difference in cognitive performance or sleep stage distribution. But subjects reported more sleepiness after a night with evening stimulation.
P277 The role of the cerebellum on motor imagery B. Cengiz, E. Boran Gazi University Faculty of Medicine, Neurology, Ankara, Turkey Introduction: It’s thought that the cerebellum plays a role in motor imagery (MI). Although there are some neuroimaging evidences support this, limited number of data investigated the role of the cerebellum on MI, in terms of neurophysiology. The aim of the this study is to explore the role of the cerebellum on MI. Cerebellar transcranial direct current stimulation (ctDCS) was used to modulate cerebellar excitability. Method: 11 healthy subjects were recruited the study (3 female, aged between 27-47, mean 33.3±8. 7). Subjects were instructed to image two different motor task. Abduction of the index finger was the simple task, while tell one’s beads was the complex one. MEPs were elicited from right first dorsal interosseous muscle. The basal MEP amplitude was calculated average values of 30 MEPs. The effect of MI on motor cortical excitability was measured by MEPs amplitude changes. Resting motor threshold (rMT), threshold for 1 mV motor evoked potential (MEP) and silent period (SP) were measured before and after ctDCS. Each subject underwent two different cerebellar modulation study: anodal stimulation and sham stimulation. The interval between experiments was at least one week. tDCS was delivered through two sponge embedded in a saline-soaked solution. Active electrode was centered on the right cerebellar cortex, 3 cm lateral to the inion. Reference electrode was positioned on the right masseter muscle. The intensity of stimulation was set at 2 mA for 20 min. Sham cTDCS consists of 30 seconds current stimulation. Results: Anodal ctDCS: • Before ctDCS: basal MEP values: 976.4±425. μV, after simple MI: 1858.2±743.7 μV (p=0.000), after complex MI: 1014.2±724. 8 μV (p>0.05). • After ctDCS: basal MEP values: 952.4±719.2 μV, after simple MI: 1202.9±376.4 μV (p>0.05), after comple.x MI: 934.8±724. 8 μV (p>0.05). Sham ctDCS: • Before ctDCS: basal MEP values: 1102.6±290.5 μV, after simple MI: 1970.2±989.9 μV (p=0.009), after complex MI: 1446.9±615.3 μV p=0.0016). • After ctDCS: basal MEP values: 1090.1±339.6 μV, after simple MI: 1857.5.9±930.2 μV (p=0, 016), after complex MI: 1421.7±785. 8 μV (p=0. 001). Conclusion: The results of the study indicate that the cerebellum modulates MI. The finding that suppression of MEP amplitude increase during MI with anodal ctDCS indicates that it has an inhibitory effect on MI.
P278 Facilitatory effects in a perceptual learning task through an “inhibitory” stimulation A. Fertonani 1 , C. Pirulli 1 , C. Miniussi 1,2 1 IRCCS Centro S. Giovanni di Dio - Fatebenefratelli, Cognitive Neuroscience Section, Brescia, Italy; 2 University of Brescia, Clinical and Experimental Sciences, Brescia, Italy Question: In the cognitive neuroscience domain no clear correlation emerges between transcranial direct current stimulation polarity (anodal a-tDCS vs. cathodal c-tDCS), and behavioural performance (improvement vs. impairment). Contradictory results are present mainly for c-tDCS. Therefore our aim was to investigate if and how some variables i.e., c-tDCS timing, pauses during c-tDCS and duration of c-tDCS affect performance, in the healthy adult brain. We applied c-tDCS before or during a task execution (before vs. during - timing), continuous vs. paused c-tDCS (yes vs. no