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EPV 25. Gamma-oscillations as a clinical marker of pain perception - a promising approach?
Abstracts / Clinical Neurophysiology 127 (2016) e210–e303
EPV 25. Gamma-oscillations as a clinical marker of pain perception - a promising approach?—U. Baumgärtner a,*, C. Heid a, A. Mouraux b, S. Schuh-Hofer a, R.- D. Treede a (a Universität Heidelberg, Medizinische Fakultät Mannheim, Lehrstuhl für Neurophysiologie, Centrum für Biomedizin und Medizintechnik Mannheim, Mannheim, Germany , b Université catholique de Louvain, Institute of Neuroscience, Brussels, Belgium) ⇑
Corresponding author.
Background: Numerous studies have used ERP-waveforms of the EEG both with nociceptive as well as tactile stimuli to answer research questions or as a functional marker of the sensory system to clinically test the integrity of signaling pathways. Recent studies brought forward the idea that gamma-band-oscillations (GBOs) between 35 and 100 Hz may play an important role in conscious perception and could be a specific marker for the perception of pain. In this study, we aimed to test whether GBOs can be reliably induced, whether they code stimulus intensity, and whether they are specific for nociceptive stimuli compared to tactile, non-nociceptive stimuli. Methods: A 17-channel EEG was recorded in 12 healthy volunteers (6 famales, 6 males) with 1 kHz continous sampling. In different blocks of 90 stimuli each, nociceptive laser stimuli of three different intensities (one intensity at pain threshold, two intensities above) and pneumatic tactile stimuli at two intensities (supra threshold; 2 and 4 bars; not painful) were delivered to the right hand and foot including one repetition, resulting in 180 stimuli per location and modality. Data were segmented into epochs of 3 s (1 sec pre stimulus interval), and subjected to a wavelet-based time frequency analysis (Letswave 5 by A. Mouraux, Brussels) in two separate analyses for the frequency ranges of 1–30 Hz and 30–100 Hz. Results: Our results indicate that there is high variability between subjects with respect to occurence and signal strength of the gamma response. Averaged across subjects, a significant increase in gamma during the first 500 ms following the stimulus was observed for nociceptive stimuli only in a frequency range between 40 and 70 Hz in close temporal relation with the evoked EEG-response in the time domain. Both, the gamma and the evoked responses increased with stimulus intensity. A clear contralateral topography restricted to the scalp area overlaying the primary somatosensory cortex was not confirmed. Conclusions: The difference in the appearance of GBOs between laser (painful) and pneumatic (tactile) stimuli could mean this response might be specific for the perception of pain. Whether higher salience of the nociceptive stimulus plays a critical role cannot be excluded. These results may help to get a better objective understanding of the perception of pain. Given the variability of individual responses, a clinical application would currently not warrant unambiguous results, but GBOs could be a promising marker in the future. Supported by Deutsche Forschungsgemeinschaft DFG SFB1158 (B05).
e231
Brain Imaging Institut, Freiburg, Germany, d Institut für e Psychologie, Freiburg, Germany, Universitätsklinikum Freiburg, Klinik für Neuroradiologie, Freiburg, Germany) ⇑
Corresponding author.
Background: Apraxia, a disorder of higher motor control, frequently leads to impaired tool use or imitation capacities due to left hemispheric lesions. However, despite similar lesion size or location, patients present with different apraxic deficits thus different early reorganization mechanism may be assumed. To understand the impaired praxis network after stroke on a functional level, we correlated behavioral performance in imitation and tool use tasks with activation patterns in fMRI of 47 acute left-hemispheric stroke patients. Methods: A cohort of 47 acute stroke patients (mean age 63.5 years ± SD 13.6; 13 female) with first ever embolic stroke in the left arteria cerebri media territory were tested for deficits in imitation of meaningless hand and finger postures and tool associated actions (pantomime of tool use, imitation of tool use, actual tool use). Testing was performed mean 4.8 days ± SD 2.9 post stroke. FMRI was acquired during presentation of video sequences of toolassociated actions viewed from a first-person perspective. Voxel wise linear regression analyses for task scores only and with lesion volume as covariate as well as group differences for categorized behavioral performance (deficit vs. no deficit) were calculated to analyze activity associated with behavioral performance in tool use and meaningless imitation. Analyses were performed using GLMflex. Results are presented on a p < 0.001 level. Results: Intact imitation of meaningless postures was associated with activation in the left middle occipital gyrus as well as in the left superior temporal lobe in linear regression analyses and categorical group differences (deficit vs. no deficit). Tool associated tasks correlated with activation in the left supramarginal gyrus and superior temporal lobe without occipital activation. For group differences in pantomime of tool use (deficit vs. no deficit) an additional activation for patients with low behavioral performance could be found in the posterior middle temporal gyrus. Conclusion: For intact imitation of meaningless postures and tool associated actions, specific left hemispheric activation patterns in the acute phase after stroke could be determined. These areas are commonly associated to the left hemispheric praxis network. While intact imitation of meaningless gestures seems to rely on intact left middle occipital gyrus for visual analysis of the presented movement tool associated actions rather seem to rely on integrity of the supramarginal gyrus, known to store movement engrams. Patients with deficits in pantomime of tool use additionally show activation of posterior middle temporal gyrus for semantic movement information. These mechanisms possibly can be interpreted as early compensatory effort. doi:10.1016/j.clinph.2016.05.057
doi:10.1016/j.clinph.2016.05.056
ePoster Presentations – Stroke EP 1. Brain activity after acute left hemispheric stroke in imitation and tool associated actions—A. Dressing a,b,c,*, L. Beume a,b,c, C.S. M. Schmidt d,c, D. Kümmerer a,c, T. Bormann a,c, I. Mader e,c, M. Rijntjes a,c, C.P. Kaller a,b,c, C. Weiller a,b,c, M. Martin a,b,c (a Universitätsklinikum Freiburg, Klinik für Neurologie und Neurophysiologie, Freiburg, Germany, b Universitätsklinikum Freiburg, BrainLinks BrainTools Cluster of Excellence, Freiburg, Germany, c Universitätsklinikum Freiburg, Freiburg
ePoster Presentations – Stroke EP 2. Pyramidal tract FA predicts motor outcome in subacute stroke patients after a three week period of arm ability training for ADL-relevant hand motor tests—M. Domin a, S. Roschka b, U. Horn a, T. Platz b, M. Lotze a,* (a University of Greifswald, Greifswald, Germany , b BDH-Klinik Greifswald, Neurorehabilitation Centre and Spinal Cord Injury Unit, Greifswald, Germany) ⇑
Corresponding author.
EPV 25. Gamma-oscillations as a clinical marker of pain perception - a promising approach?—U. Baumgärtner a,*, C. Heid a, A. Mouraux b, S. Schuh-Hofer a, R.- D. Treede a (a Universität Heidelberg, Medizinische Fakultät Mannheim, Lehrstuhl für Neurophysiologie, Centrum für Biomedizin und Medizintechnik Mannheim, Mannheim, Germany , b Université catholique de Louvain, Institute of Neuroscience, Brussels, Belgium) ⇑
Corresponding author.
Background: Numerous studies have used ERP-waveforms of the EEG both with nociceptive as well as tactile stimuli to answer research questions or as a functional marker of the sensory system to clinically test the integrity of signaling pathways. Recent studies brought forward the idea that gamma-band-oscillations (GBOs) between 35 and 100 Hz may play an important role in conscious perception and could be a specific marker for the perception of pain. In this study, we aimed to test whether GBOs can be reliably induced, whether they code stimulus intensity, and whether they are specific for nociceptive stimuli compared to tactile, non-nociceptive stimuli. Methods: A 17-channel EEG was recorded in 12 healthy volunteers (6 famales, 6 males) with 1 kHz continous sampling. In different blocks of 90 stimuli each, nociceptive laser stimuli of three different intensities (one intensity at pain threshold, two intensities above) and pneumatic tactile stimuli at two intensities (supra threshold; 2 and 4 bars; not painful) were delivered to the right hand and foot including one repetition, resulting in 180 stimuli per location and modality. Data were segmented into epochs of 3 s (1 sec pre stimulus interval), and subjected to a wavelet-based time frequency analysis (Letswave 5 by A. Mouraux, Brussels) in two separate analyses for the frequency ranges of 1–30 Hz and 30–100 Hz. Results: Our results indicate that there is high variability between subjects with respect to occurence and signal strength of the gamma response. Averaged across subjects, a significant increase in gamma during the first 500 ms following the stimulus was observed for nociceptive stimuli only in a frequency range between 40 and 70 Hz in close temporal relation with the evoked EEG-response in the time domain. Both, the gamma and the evoked responses increased with stimulus intensity. A clear contralateral topography restricted to the scalp area overlaying the primary somatosensory cortex was not confirmed. Conclusions: The difference in the appearance of GBOs between laser (painful) and pneumatic (tactile) stimuli could mean this response might be specific for the perception of pain. Whether higher salience of the nociceptive stimulus plays a critical role cannot be excluded. These results may help to get a better objective understanding of the perception of pain. Given the variability of individual responses, a clinical application would currently not warrant unambiguous results, but GBOs could be a promising marker in the future. Supported by Deutsche Forschungsgemeinschaft DFG SFB1158 (B05).
e231
Brain Imaging Institut, Freiburg, Germany, d Institut für e Psychologie, Freiburg, Germany, Universitätsklinikum Freiburg, Klinik für Neuroradiologie, Freiburg, Germany) ⇑
Corresponding author.
Background: Apraxia, a disorder of higher motor control, frequently leads to impaired tool use or imitation capacities due to left hemispheric lesions. However, despite similar lesion size or location, patients present with different apraxic deficits thus different early reorganization mechanism may be assumed. To understand the impaired praxis network after stroke on a functional level, we correlated behavioral performance in imitation and tool use tasks with activation patterns in fMRI of 47 acute left-hemispheric stroke patients. Methods: A cohort of 47 acute stroke patients (mean age 63.5 years ± SD 13.6; 13 female) with first ever embolic stroke in the left arteria cerebri media territory were tested for deficits in imitation of meaningless hand and finger postures and tool associated actions (pantomime of tool use, imitation of tool use, actual tool use). Testing was performed mean 4.8 days ± SD 2.9 post stroke. FMRI was acquired during presentation of video sequences of toolassociated actions viewed from a first-person perspective. Voxel wise linear regression analyses for task scores only and with lesion volume as covariate as well as group differences for categorized behavioral performance (deficit vs. no deficit) were calculated to analyze activity associated with behavioral performance in tool use and meaningless imitation. Analyses were performed using GLMflex. Results are presented on a p < 0.001 level. Results: Intact imitation of meaningless postures was associated with activation in the left middle occipital gyrus as well as in the left superior temporal lobe in linear regression analyses and categorical group differences (deficit vs. no deficit). Tool associated tasks correlated with activation in the left supramarginal gyrus and superior temporal lobe without occipital activation. For group differences in pantomime of tool use (deficit vs. no deficit) an additional activation for patients with low behavioral performance could be found in the posterior middle temporal gyrus. Conclusion: For intact imitation of meaningless postures and tool associated actions, specific left hemispheric activation patterns in the acute phase after stroke could be determined. These areas are commonly associated to the left hemispheric praxis network. While intact imitation of meaningless gestures seems to rely on intact left middle occipital gyrus for visual analysis of the presented movement tool associated actions rather seem to rely on integrity of the supramarginal gyrus, known to store movement engrams. Patients with deficits in pantomime of tool use additionally show activation of posterior middle temporal gyrus for semantic movement information. These mechanisms possibly can be interpreted as early compensatory effort. doi:10.1016/j.clinph.2016.05.057
doi:10.1016/j.clinph.2016.05.056
ePoster Presentations – Stroke EP 1. Brain activity after acute left hemispheric stroke in imitation and tool associated actions—A. Dressing a,b,c,*, L. Beume a,b,c, C.S. M. Schmidt d,c, D. Kümmerer a,c, T. Bormann a,c, I. Mader e,c, M. Rijntjes a,c, C.P. Kaller a,b,c, C. Weiller a,b,c, M. Martin a,b,c (a Universitätsklinikum Freiburg, Klinik für Neurologie und Neurophysiologie, Freiburg, Germany, b Universitätsklinikum Freiburg, BrainLinks BrainTools Cluster of Excellence, Freiburg, Germany, c Universitätsklinikum Freiburg, Freiburg
ePoster Presentations – Stroke EP 2. Pyramidal tract FA predicts motor outcome in subacute stroke patients after a three week period of arm ability training for ADL-relevant hand motor tests—M. Domin a, S. Roschka b, U. Horn a, T. Platz b, M. Lotze a,* (a University of Greifswald, Greifswald, Germany , b BDH-Klinik Greifswald, Neurorehabilitation Centre and Spinal Cord Injury Unit, Greifswald, Germany) ⇑
Corresponding author.