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P315 Investigating bimanual motor coordination in healthy young and older adults using EEG and transcranial direct current stimulation (tDCS)
e114
Abstracts / Clinical Neurophysiology 128 (2017) e1–e163
cognitive and neural mechanisms can give valuable insights and pave the ground for exploring tCS as a treatment option in future studies. Objectives: We aim to investigate the neural changes underlying tACS on the angular gyrus in MCI patients and in healthy controls using simultaneous fMRI, and the effect of repeated vs. firstsession tACS. Performance on a memory task will be compared between sessions. A hippocampus-driven pattern separation memory task will be implemented to investigate if tACS vs. sham during the encoding and consolidation phase has an influence on brain activation during subsequent retrieval. Transfer to a similar, non-practiced task will be assessed at follow-up. Patients & methods or materials & methods: 20 MCI patients and 20 healthy controls will receive 1 sham-tACS session, 5 consecutive tACS-sessions, and one follow-up session. FMRI-scans will be obtained during sham, on the first and fifth active session and one week after the last active session. TACS will be applied online during encoding (task-fMRI) and consolidation (resting-state-fMRI) of a pattern separation task. Parallel task-versions will be used in randomized order to minimize learning effects. Within- and between group analyses will be conducted on both the fMRI-data (task and rs-fMRI) and the behavioural data (pattern separation performance). doi:10.1016/j.clinph.2016.10.322
P206 Cross-hemispheric frontoparietal desynchronization impairs the visual-spatial working memory in humans—I. Alekseichuk *, S.C. Pabel, A. Antal, W. Paulus (University Medical Center Göttingen, Dept. of Clinical Neurophysiology, Göttingen, Germany) ⇑
Corresponding author.
Introduction: Multiple studies indicated the left and right prefrontal cortex (PFC) and posterior parietal cortex (PPC) as anatomical substrates of the spatial working memory (i.e. frontoparietal memory network), however, the exact functional connectivity between these areas remains uncertain. This is partly due to the limitations of the applied neuroimaging methodologies, which are correlative in nature, as well as the classical brain stimulation approaches that are mostly operate within the limited number of neocortical sites. Objectives: Here, we are taking advantages of the novel multichannel transcranial alternating current stimulation (tACS) method in order to investigate the role of phase connectivity between the frontoparietal regions in the left and right hemispheres that are commonly associated with the visual-spatial working memory related behavior. Materials & methods: Fifteen healthy volunteers (11 females, age range: 19–28 years) participated in this double-blinded, placebocontrolled, randomized, crossover study. Each of them completed a 2-back visual-spatial working memory test during tACS and sham stimulation. Multichannel stimulation was applied at an intensity of 1 mA peak-to-baseline with a frequency of 6 Hz over the left PFC and PPC versus the right PFC and PPC. The working memory performance was estimated according to the signal detection theory as 0 follows: d = Z(‘‘hit rate”) Z(‘‘false alarm rate”); and compared using the paired t-test. Results: We observed the significant decrease in working memory performance during the desynchronization of the left and right fron0 toparietal regions in comparison to the control: dcontrol = 2.58 ± 0.12 0 (mean ± s.e.m.) and ddesynch = 2.34 ± 0.11 (T(14) = 2.44, p = 0.03). No
significant differences in the skin sensations and phosphenes were perceived according to the post-session written reports. Conclusion: The efficiency of visual-spatial working memory in humans depends on the precisely calibrated phase connectivity within the frontoparietal network. Desynchronization of these relationships leads to the significant impairment of working memory performance. doi:10.1016/j.clinph.2016.10.323
P207 Affecting declarative long-term memory with transcranial alternating current stimulation (tACS)—G. de Lara * , I. Alekseichuk, Z. Turi, A. Antal, W. Paulus (University Medical Center Göttingen, Department Clinical Neurophysiology, Göttingen, Germany) ⇑
Corresponding author.
Introduction and objective: Previous studies imply that tACS can entrain the ongoing physiological neuronal oscillations depending on the targeted function and the parameters (frequency, intensity and phase) of the stimulation. The aim of the present study was to clarify if tACScould influence the performance of healthy subjects on a verbal paired-associate learning paradigm. Methods: For that, we conducted three different crossover, randomized, single-blind, placebo-controlled studies, using a batterydriven Starstim stimulator system (Neuroelectrics, Barcelona, Spain). In the first study (n = 6), we applied 100 Hz tACS with 1.5 mA (active electrode T7, return Fpz and T8); in the second one (n = 6), 1.0 mA, 6 Hz (3 s) followed by 80 Hz (5 s) tACS during ISI and Stimulus presentation using the same electrodes configuration; in the third one (n = 15), we combined a temporal- and pre-frontal stimulation using 7 electrodes. Here the stimulation intensity was 1 mA at 6 Hz (temporal) and 80 Hz (pre-frontal) combined stimulation. For all the studies, we used 8 cm 2 round rubber electrodes inside a saline-soaked sponge pocket, applying 10 min stimulation during the word-pairs learning phase. After the learning phase, the subjects had a 10 min pause, followed by a test phase with a cued recall. The subjects returned after 24 h for a second cued-recall test. All subjects receivedactive and sham tACS in a counterbalanced, randomized-manner. Results: In the first two studies, no significant difference were found in the accuracy performance between days across conditions, as well as between days within conditions; in the third study, we found no significant difference between days across conditions, but significant difference between days in the active (t = 2.98, p = 0.010) and sham (t = 2.52, p = 0.024) stimulation. Conclusion: The stimulation parameters tested could not influence the memory performance assessed by this memory task with the present number of subjects in the first two studies. Further variations of waveforms, intensity and stimulation parameters should be tested with the same task in order to probe the possible influence of tACS on episodic long-term memory. The final results will be presented in the conference. doi:10.1016/j.clinph.2016.10.324
P315 Investigating bimanual motor coordination in healthy young and older adults using EEG and transcranial direct current stimulation (tDCS)—A. Jamil a,b,d,*, K. Cuypers b,c, M.A. Nitsche a,d,e, R. Meesen b,c (a University of Göttingen, Göttingen, Germany,
Abstracts / Clinical Neurophysiology 128 (2017) e1–e163
e115
Figure 1.
b
University of Hasselt, Hasselt, Belgium , c Katholieke University of Leuven, Leuven, Belgium, d Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany, e University Medical Hospital Bergmannsheil, Bochum, Germany) ⇑
Corresponding author.
Introduction: Accompanying the natural advancing of age is a decline in cognitive and motor functions, which can significantly impact the daily life activities in the elder demographic (>65 y). Such declines may involve altered neuroplasticity, due to changes in synaptic function and neurotransmission. Successful performance of complex motor tasks may also entail distinct patterns in motor cortical functional connectivity, which may also be subject to age related changes. On the other hand, recent work has shown that transcranial direct current stimulation (tDCS) may be a useful tool to restitute these altered mechanisms, and improve performance of motor skills. Objectives: The present study first addresses the question of identifying physiological markers of age-related differences during acquisition and performance of bimanual motor movements, based on motor cortical functional connectivity using EEG. Second, the study assesses whether performance of complex bimanual motor skills can be improved in the elderly using tDCS. Methods: Experiment 1: 42 healthy, non-smoking subjects (20 young/22 elderly) were recruited. Subjects performed a bimanual tracking task similar to the classic ‘‘Etch-a-Sketch” game, which requires in-phase and anti-phase movements, and at various frequencies. Three blocks of the task were performed (180 total trials) in the single-session design to evaluate both kinematic and EEG metrics (phase lag functional connectivity) between the young and elderly. Experiment 2: An additional 40 subjects (20 young/20 elderly) were recruited for evaluating whether right M1 anodal tDCS (1.0 mA, 20 min) may improve performance in the task. A doubleblinded, sham-controlled, randomized crossover design was implemented to assess kinematic and functional connectivity differences between young and elderly. Data was statistically analyzed within the framework of mixeddesign ANOVAs, in order to assess overall group differences in performance, as well as main effects of stimulation, across three incrementing levels of task difficulty. Results: Experiment 1: Task performance in younger subjects was more accurate than elderly. Elderly showed higher beta power during planning and performance periods. Lateralized motor cortical functional connectivity to prefrontal cortical areas was also greater in younger subjects, whereas elderly subjects showed no discrimination in activation during tasks that relied more on one hand.
Experiment 2: ANOVA revealed a main effect of stimulation in elderly but not in young. Post hoc analyses revealed significant improvements in both left and right hand coordination in real stimulation conditions. Younger subjects tended to improve performance as well, although ceilings effects may have been a constraint. In further post hoc analyses, we observed that older subjects favored slower, but accurate movement coordination whereas younger participants divided evenly in the speed vs. accuracy dichotomy. Conclusion: We show that both functional connectivity and interlimb kinematics underlying bimanual motor coordination are different between the young and elderly. Such differences may be due to constraints in muscular strength, degeneration of the gray matter, and/or differences in cortical connectivity as a result of the aging process. We further show that a single session of tDCS applied to the motor cortex was able to significantly improve the bimanual performance in both young and elderly. Although further studies are needed to optimize tDCS parameters for enhanced and prolonged effects, this non-invasive stimulation technique may be a viable tool in restituting and even further optimizing motor functioning. doi:10.1016/j.clinph.2016.10.325
TMS – What is stimulated Beyond M1 P208 The effects of transcutaneous spinal cord stimulation on spinal reciprocal inhibition in healthy persons—T. Yamaguchi a,*, T. Fujiwara b, T. Takahara a, Y. Takahashi a, K. Mizuno a, J. Ushiba c, Y. Masakado b, M. Liu a (a University School of Medicine, Department of Rehabilitation Medicine, Tokyo, Japan, b Tokai University School of Medicine, Department of Rehabilitation Medicine, Kanagawa, Japan, c Keio University, Department of Biosciences and Informatics, Faculty of Science and Technology, Kanagawa, Japan) ⇑
Corresponding author.
Introduction: Transcutaneous spinal cord stimulation (tSCS) is a non-invasive method to stimulate afferent structures of the spinal neural circuits related with lower limb motor control. Its application is known to improve lower limb motor function in individuals with spinal cord injury. However, it remains unknown whether tSCS induces spinal plasticity, which has an essential role in functional recovery of the lower limb after spinal cord injury and stroke. Objectives: The purpose of this study was to investigate the effects of tSCS on spinal reciprocal inhibition in healthy individuals.
Abstracts / Clinical Neurophysiology 128 (2017) e1–e163
cognitive and neural mechanisms can give valuable insights and pave the ground for exploring tCS as a treatment option in future studies. Objectives: We aim to investigate the neural changes underlying tACS on the angular gyrus in MCI patients and in healthy controls using simultaneous fMRI, and the effect of repeated vs. firstsession tACS. Performance on a memory task will be compared between sessions. A hippocampus-driven pattern separation memory task will be implemented to investigate if tACS vs. sham during the encoding and consolidation phase has an influence on brain activation during subsequent retrieval. Transfer to a similar, non-practiced task will be assessed at follow-up. Patients & methods or materials & methods: 20 MCI patients and 20 healthy controls will receive 1 sham-tACS session, 5 consecutive tACS-sessions, and one follow-up session. FMRI-scans will be obtained during sham, on the first and fifth active session and one week after the last active session. TACS will be applied online during encoding (task-fMRI) and consolidation (resting-state-fMRI) of a pattern separation task. Parallel task-versions will be used in randomized order to minimize learning effects. Within- and between group analyses will be conducted on both the fMRI-data (task and rs-fMRI) and the behavioural data (pattern separation performance). doi:10.1016/j.clinph.2016.10.322
P206 Cross-hemispheric frontoparietal desynchronization impairs the visual-spatial working memory in humans—I. Alekseichuk *, S.C. Pabel, A. Antal, W. Paulus (University Medical Center Göttingen, Dept. of Clinical Neurophysiology, Göttingen, Germany) ⇑
Corresponding author.
Introduction: Multiple studies indicated the left and right prefrontal cortex (PFC) and posterior parietal cortex (PPC) as anatomical substrates of the spatial working memory (i.e. frontoparietal memory network), however, the exact functional connectivity between these areas remains uncertain. This is partly due to the limitations of the applied neuroimaging methodologies, which are correlative in nature, as well as the classical brain stimulation approaches that are mostly operate within the limited number of neocortical sites. Objectives: Here, we are taking advantages of the novel multichannel transcranial alternating current stimulation (tACS) method in order to investigate the role of phase connectivity between the frontoparietal regions in the left and right hemispheres that are commonly associated with the visual-spatial working memory related behavior. Materials & methods: Fifteen healthy volunteers (11 females, age range: 19–28 years) participated in this double-blinded, placebocontrolled, randomized, crossover study. Each of them completed a 2-back visual-spatial working memory test during tACS and sham stimulation. Multichannel stimulation was applied at an intensity of 1 mA peak-to-baseline with a frequency of 6 Hz over the left PFC and PPC versus the right PFC and PPC. The working memory performance was estimated according to the signal detection theory as 0 follows: d = Z(‘‘hit rate”) Z(‘‘false alarm rate”); and compared using the paired t-test. Results: We observed the significant decrease in working memory performance during the desynchronization of the left and right fron0 toparietal regions in comparison to the control: dcontrol = 2.58 ± 0.12 0 (mean ± s.e.m.) and ddesynch = 2.34 ± 0.11 (T(14) = 2.44, p = 0.03). No
significant differences in the skin sensations and phosphenes were perceived according to the post-session written reports. Conclusion: The efficiency of visual-spatial working memory in humans depends on the precisely calibrated phase connectivity within the frontoparietal network. Desynchronization of these relationships leads to the significant impairment of working memory performance. doi:10.1016/j.clinph.2016.10.323
P207 Affecting declarative long-term memory with transcranial alternating current stimulation (tACS)—G. de Lara * , I. Alekseichuk, Z. Turi, A. Antal, W. Paulus (University Medical Center Göttingen, Department Clinical Neurophysiology, Göttingen, Germany) ⇑
Corresponding author.
Introduction and objective: Previous studies imply that tACS can entrain the ongoing physiological neuronal oscillations depending on the targeted function and the parameters (frequency, intensity and phase) of the stimulation. The aim of the present study was to clarify if tACScould influence the performance of healthy subjects on a verbal paired-associate learning paradigm. Methods: For that, we conducted three different crossover, randomized, single-blind, placebo-controlled studies, using a batterydriven Starstim stimulator system (Neuroelectrics, Barcelona, Spain). In the first study (n = 6), we applied 100 Hz tACS with 1.5 mA (active electrode T7, return Fpz and T8); in the second one (n = 6), 1.0 mA, 6 Hz (3 s) followed by 80 Hz (5 s) tACS during ISI and Stimulus presentation using the same electrodes configuration; in the third one (n = 15), we combined a temporal- and pre-frontal stimulation using 7 electrodes. Here the stimulation intensity was 1 mA at 6 Hz (temporal) and 80 Hz (pre-frontal) combined stimulation. For all the studies, we used 8 cm 2 round rubber electrodes inside a saline-soaked sponge pocket, applying 10 min stimulation during the word-pairs learning phase. After the learning phase, the subjects had a 10 min pause, followed by a test phase with a cued recall. The subjects returned after 24 h for a second cued-recall test. All subjects receivedactive and sham tACS in a counterbalanced, randomized-manner. Results: In the first two studies, no significant difference were found in the accuracy performance between days across conditions, as well as between days within conditions; in the third study, we found no significant difference between days across conditions, but significant difference between days in the active (t = 2.98, p = 0.010) and sham (t = 2.52, p = 0.024) stimulation. Conclusion: The stimulation parameters tested could not influence the memory performance assessed by this memory task with the present number of subjects in the first two studies. Further variations of waveforms, intensity and stimulation parameters should be tested with the same task in order to probe the possible influence of tACS on episodic long-term memory. The final results will be presented in the conference. doi:10.1016/j.clinph.2016.10.324
P315 Investigating bimanual motor coordination in healthy young and older adults using EEG and transcranial direct current stimulation (tDCS)—A. Jamil a,b,d,*, K. Cuypers b,c, M.A. Nitsche a,d,e, R. Meesen b,c (a University of Göttingen, Göttingen, Germany,
Abstracts / Clinical Neurophysiology 128 (2017) e1–e163
e115
Figure 1.
b
University of Hasselt, Hasselt, Belgium , c Katholieke University of Leuven, Leuven, Belgium, d Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany, e University Medical Hospital Bergmannsheil, Bochum, Germany) ⇑
Corresponding author.
Introduction: Accompanying the natural advancing of age is a decline in cognitive and motor functions, which can significantly impact the daily life activities in the elder demographic (>65 y). Such declines may involve altered neuroplasticity, due to changes in synaptic function and neurotransmission. Successful performance of complex motor tasks may also entail distinct patterns in motor cortical functional connectivity, which may also be subject to age related changes. On the other hand, recent work has shown that transcranial direct current stimulation (tDCS) may be a useful tool to restitute these altered mechanisms, and improve performance of motor skills. Objectives: The present study first addresses the question of identifying physiological markers of age-related differences during acquisition and performance of bimanual motor movements, based on motor cortical functional connectivity using EEG. Second, the study assesses whether performance of complex bimanual motor skills can be improved in the elderly using tDCS. Methods: Experiment 1: 42 healthy, non-smoking subjects (20 young/22 elderly) were recruited. Subjects performed a bimanual tracking task similar to the classic ‘‘Etch-a-Sketch” game, which requires in-phase and anti-phase movements, and at various frequencies. Three blocks of the task were performed (180 total trials) in the single-session design to evaluate both kinematic and EEG metrics (phase lag functional connectivity) between the young and elderly. Experiment 2: An additional 40 subjects (20 young/20 elderly) were recruited for evaluating whether right M1 anodal tDCS (1.0 mA, 20 min) may improve performance in the task. A doubleblinded, sham-controlled, randomized crossover design was implemented to assess kinematic and functional connectivity differences between young and elderly. Data was statistically analyzed within the framework of mixeddesign ANOVAs, in order to assess overall group differences in performance, as well as main effects of stimulation, across three incrementing levels of task difficulty. Results: Experiment 1: Task performance in younger subjects was more accurate than elderly. Elderly showed higher beta power during planning and performance periods. Lateralized motor cortical functional connectivity to prefrontal cortical areas was also greater in younger subjects, whereas elderly subjects showed no discrimination in activation during tasks that relied more on one hand.
Experiment 2: ANOVA revealed a main effect of stimulation in elderly but not in young. Post hoc analyses revealed significant improvements in both left and right hand coordination in real stimulation conditions. Younger subjects tended to improve performance as well, although ceilings effects may have been a constraint. In further post hoc analyses, we observed that older subjects favored slower, but accurate movement coordination whereas younger participants divided evenly in the speed vs. accuracy dichotomy. Conclusion: We show that both functional connectivity and interlimb kinematics underlying bimanual motor coordination are different between the young and elderly. Such differences may be due to constraints in muscular strength, degeneration of the gray matter, and/or differences in cortical connectivity as a result of the aging process. We further show that a single session of tDCS applied to the motor cortex was able to significantly improve the bimanual performance in both young and elderly. Although further studies are needed to optimize tDCS parameters for enhanced and prolonged effects, this non-invasive stimulation technique may be a viable tool in restituting and even further optimizing motor functioning. doi:10.1016/j.clinph.2016.10.325
TMS – What is stimulated Beyond M1 P208 The effects of transcutaneous spinal cord stimulation on spinal reciprocal inhibition in healthy persons—T. Yamaguchi a,*, T. Fujiwara b, T. Takahara a, Y. Takahashi a, K. Mizuno a, J. Ushiba c, Y. Masakado b, M. Liu a (a University School of Medicine, Department of Rehabilitation Medicine, Tokyo, Japan, b Tokai University School of Medicine, Department of Rehabilitation Medicine, Kanagawa, Japan, c Keio University, Department of Biosciences and Informatics, Faculty of Science and Technology, Kanagawa, Japan) ⇑
Corresponding author.
Introduction: Transcutaneous spinal cord stimulation (tSCS) is a non-invasive method to stimulate afferent structures of the spinal neural circuits related with lower limb motor control. Its application is known to improve lower limb motor function in individuals with spinal cord injury. However, it remains unknown whether tSCS induces spinal plasticity, which has an essential role in functional recovery of the lower limb after spinal cord injury and stroke. Objectives: The purpose of this study was to investigate the effects of tSCS on spinal reciprocal inhibition in healthy individuals.