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P 49. Modulation of spontaneous and TMS-evoked alpha oscillations by top-down visual attention
Society Proceedings / Clinical Neurophysiology 124 (2013) e39–e187
(QPS)-5 ms, a newly devised rTMS protocol which produces longterm potentiation (LTP) like aftereffect. QPS over SMA, QPS over the primary motor cortex (M1), and sham QPS were compared. In addition, amplitude of motor evoked potential (MEP) from the first dorsal interosseous (FDI) muscles, resting and active motor thresholds (RMT and AMT) were measured as a physiological parameter. Results: QPS over SMA diminished NCE of both hands, whereas QPS over M1 and sham QPS had no effect. CRT was similar among the QPS protocols, but PCE with the right hand tended to be enhanced by QPS over SMA. With regard to the physiological markers, MEP amplitude of right FDI tended to be increased by QPS. RMT and AMT were unchanged in any conditions. Conclusions: The present results indicate that SMA plays a causal role to express NCE. The mechanism of PCE enhancement and its relation to NCE decrease needs to be studied in a future research. doi:10.1016/j.clinph.2013.04.126
P 49. Modulation of spontaneous and TMS-evoked alpha oscillations by top-down visual attention—J. Herring a, G. Thut b,c, O. Jensen a, T. Bergmann a (a Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands, b Institute for Neuroscience and Psychology, Centre for Cognitive Neuroimaging (CCNi), Glasgow, United Kingdom, c University of Glasgow, School of Psychology, Glasgow, United Kingdom) Introduction: Simultaneous transcranial magnetic stimulation (TMS) and electroencephalography (EEG) allows the direct assessment of cortico-thalamic responsiveness by TMS-evoked EEG potentials (TEPs). Notably, the frequency composition of TEPs corresponds to the dominant spontaneous oscillation at the respective stimulation site, e.g. 0 alpha0 in the visual cortex (Rosanova et al., J Neurosci 2009). Furthermore, TEPs change dramatically with shifts in neuromodulatory levels during sleep (Massimini et al., Science 2005; Bergmann et al., J Neurosci 2012), suggesting that both are generated by the same neuronal mechanisms. Indeed, rhythmic TMS of the parieto-occipital cortex can mimic alpha band (8–12 Hz) oscillations in the EEG (Thut et al., Curr Biol 2011) as well as their known impact on perceptual performance (Romei et al., J Neurosci 2010) due to gat-
e87
ing by inhibition (Jensen et al., TICS 2012). However, does the alphalike TEP as response to visual cortex stimulation actually resemble spontaneous alpha oscillations or rather visual evoked potentials (VEPs)? Importantly, VEPs are amplified by visual attention (Rajagovindan and Ding, J Cog Neurosci, 2011), whereas spontaneous alpha oscillations are suppressed (Foxe et al., Neurorep 1998; Fu et al., Cog Brain Res 2001). Objectives: To test the similarity between transcranially evoked and spontaneous alpha oscillations, we currently investigate whether they show comparable responses to covert shifts in attention, i.e., decrease and increase in amplitude when attending the visual and auditory modality, respectively (Foxe and Snyder, Front Psychol 2011). Methods: Here, we measure TEPs my means of simultaneously applied 61-channel EEG and neuronavigated single-pulse TMS to the visual cortex while subjects attend to either visual or auditory noise patterns in order to detect slight contrast modulations. Since auditory stimuli have been shown to evoke an alpha-like response in the visual cortex (Romei, Gross and Thut, Curr Biol 2012), we use a constant stream of auditory masking noise as well as sham TMS to control for these effects. Results and conclusion: Preliminary results suggest that the TMSevoked alpha oscillation is in fact modulated by top-down visual attention in analogy to spontaneous alpha oscillations, suggesting that both are generated by the same underlying neural mechanisms. doi:10.1016/j.clinph.2013.04.127
P 50. Anodal cerebellar tDCS impairs verbal working memory—K. Macher a, A. Böhringer b, A. Villringer a,c,d, B. Pleger a,d (a Max Planck Institute for Human Cognitive and Brain Sciences, Neurology, Leipzig, Germany, b Central Institute for Mental Health, Mannheim, Germany, c Berlin School of Mind and Brain, Mind and Brain Institute, Berlin, Germany, d Dept. of Cognitive Neurology, University Hospital Leipzig, Leipzig, Germany) Introduction: The cerebellum is not only engaged in sensorymotor function but also cognitive processes like attention and perception (Stoodley and Schmahmann, 2009). The verbal working memory is one of these cognitive processes. Growing evidence
(QPS)-5 ms, a newly devised rTMS protocol which produces longterm potentiation (LTP) like aftereffect. QPS over SMA, QPS over the primary motor cortex (M1), and sham QPS were compared. In addition, amplitude of motor evoked potential (MEP) from the first dorsal interosseous (FDI) muscles, resting and active motor thresholds (RMT and AMT) were measured as a physiological parameter. Results: QPS over SMA diminished NCE of both hands, whereas QPS over M1 and sham QPS had no effect. CRT was similar among the QPS protocols, but PCE with the right hand tended to be enhanced by QPS over SMA. With regard to the physiological markers, MEP amplitude of right FDI tended to be increased by QPS. RMT and AMT were unchanged in any conditions. Conclusions: The present results indicate that SMA plays a causal role to express NCE. The mechanism of PCE enhancement and its relation to NCE decrease needs to be studied in a future research. doi:10.1016/j.clinph.2013.04.126
P 49. Modulation of spontaneous and TMS-evoked alpha oscillations by top-down visual attention—J. Herring a, G. Thut b,c, O. Jensen a, T. Bergmann a (a Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands, b Institute for Neuroscience and Psychology, Centre for Cognitive Neuroimaging (CCNi), Glasgow, United Kingdom, c University of Glasgow, School of Psychology, Glasgow, United Kingdom) Introduction: Simultaneous transcranial magnetic stimulation (TMS) and electroencephalography (EEG) allows the direct assessment of cortico-thalamic responsiveness by TMS-evoked EEG potentials (TEPs). Notably, the frequency composition of TEPs corresponds to the dominant spontaneous oscillation at the respective stimulation site, e.g. 0 alpha0 in the visual cortex (Rosanova et al., J Neurosci 2009). Furthermore, TEPs change dramatically with shifts in neuromodulatory levels during sleep (Massimini et al., Science 2005; Bergmann et al., J Neurosci 2012), suggesting that both are generated by the same neuronal mechanisms. Indeed, rhythmic TMS of the parieto-occipital cortex can mimic alpha band (8–12 Hz) oscillations in the EEG (Thut et al., Curr Biol 2011) as well as their known impact on perceptual performance (Romei et al., J Neurosci 2010) due to gat-
e87
ing by inhibition (Jensen et al., TICS 2012). However, does the alphalike TEP as response to visual cortex stimulation actually resemble spontaneous alpha oscillations or rather visual evoked potentials (VEPs)? Importantly, VEPs are amplified by visual attention (Rajagovindan and Ding, J Cog Neurosci, 2011), whereas spontaneous alpha oscillations are suppressed (Foxe et al., Neurorep 1998; Fu et al., Cog Brain Res 2001). Objectives: To test the similarity between transcranially evoked and spontaneous alpha oscillations, we currently investigate whether they show comparable responses to covert shifts in attention, i.e., decrease and increase in amplitude when attending the visual and auditory modality, respectively (Foxe and Snyder, Front Psychol 2011). Methods: Here, we measure TEPs my means of simultaneously applied 61-channel EEG and neuronavigated single-pulse TMS to the visual cortex while subjects attend to either visual or auditory noise patterns in order to detect slight contrast modulations. Since auditory stimuli have been shown to evoke an alpha-like response in the visual cortex (Romei, Gross and Thut, Curr Biol 2012), we use a constant stream of auditory masking noise as well as sham TMS to control for these effects. Results and conclusion: Preliminary results suggest that the TMSevoked alpha oscillation is in fact modulated by top-down visual attention in analogy to spontaneous alpha oscillations, suggesting that both are generated by the same underlying neural mechanisms. doi:10.1016/j.clinph.2013.04.127
P 50. Anodal cerebellar tDCS impairs verbal working memory—K. Macher a, A. Böhringer b, A. Villringer a,c,d, B. Pleger a,d (a Max Planck Institute for Human Cognitive and Brain Sciences, Neurology, Leipzig, Germany, b Central Institute for Mental Health, Mannheim, Germany, c Berlin School of Mind and Brain, Mind and Brain Institute, Berlin, Germany, d Dept. of Cognitive Neurology, University Hospital Leipzig, Leipzig, Germany) Introduction: The cerebellum is not only engaged in sensorymotor function but also cognitive processes like attention and perception (Stoodley and Schmahmann, 2009). The verbal working memory is one of these cognitive processes. Growing evidence