Volume 106, Issue 1, Pages 103-112 (September 2013) TMS-EEG reveals impaired intracortical interactions and coherence in Unverricht- Lundborg type progressive myoclonus epilepsy (EPM1)  Petro Julkunen, Laura Säisänen, Mervi Könönen, Ritva Vanninen, Reetta Kälviäinen, Esa Mervaala  Epilepsy Research  Volume 106, Issue 1, Pages 103-112 (September 2013) DOI: 10.1016/j.eplepsyres.2013.04.001 Copyright © 2013 Elsevier B.V. Terms and Conditions

Figure 1 (A) TMS-EEG response and (B) electrode layout. In the TMS-EEG response, three analysed peaks are visible, P30, N100 and P180. Two amplitudes were analysed, the P30 deflection from the baseline and the peak-to-peak amplitude between peaks N100 and P180. The TMS-EEG response is an average response from 10 electrodes in the vicinity of the stimulation site shown in the EEG-electrode layout in B. The shown layout of the EEG-electrodes in the EEG-cap was used in recording the TMS-EEG responses. The EEG was referenced on the right mastoid. The stimulations were focused on the M1, and electrode 27 (highlighted) was used in computing the time-frequency dependent event-related spectral perturburation (ERSP) and inter-trial coherence (ITC), and choosing the appropriate frequency bands and time-windows at which topographical comparisons were conducted. The region-of-interest (indicated with a dashed line) over which channels were averaged for the peak analysis of the TMS-EEG responses. Epilepsy Research 2013 106, 103-112DOI: (10.1016/j.eplepsyres.2013.04.001) Copyright © 2013 Elsevier B.V. Terms and Conditions

Figure 2 Global field power. Averaged GFP for the controls (black line) and EPM1 patients (dashed red line). The grey background indicates time-frames at which there is a significant difference (p<0.05) in the GFP between controls and patients. Epilepsy Research 2013 106, 103-112DOI: (10.1016/j.eplepsyres.2013.04.001) Copyright © 2013 Elsevier B.V. Terms and Conditions

Figure 3 ERSP and ITC. The group-wise mean event-related spectral perturbation (ERSP, above) and inter-trial coherence (ITC, below) measured from channel 27 (Fig. 1B). By visual inspection clear differences in the ERSP as well as ITC can be observed between the groups, most of which occur at the alpha and beta bands, and soon after the TMS. Epilepsy Research 2013 106, 103-112DOI: (10.1016/j.eplepsyres.2013.04.001) Copyright © 2013 Elsevier B.V. Terms and Conditions

Figure 4 Early ERSP and ITC in the alpha band. Comparison of alpha band ERSP (panel above) and ITC (panel below) distribution between the groups. The time-window over which the ERSP and ITC were averaged within each individual subject was 25–100ms, chosen based on Fig. 2. The topographical averages computed for each channel are presented on the left side (for controls above and for EPM1 patients below). On the right side of the topographical average maps, a p-value map is presented to observe areas with statistically significant differences in ERSP or ITC. In the ERSP, the significantly different sites are above the M1 ipsilateral to TMS as well as contralaterally. In the ITC, most of the recorded EEG electrodes indicated significantly higher phase coherence in controls as compared to EPM1 patients. Epilepsy Research 2013 106, 103-112DOI: (10.1016/j.eplepsyres.2013.04.001) Copyright © 2013 Elsevier B.V. Terms and Conditions

Figure 5 Late ERSP and ITC in the alpha band. Comparison of alpha band ERSP (panel above) and ITC (panel below) distribution between the groups. The time-window over which the ERSP and ITC were averaged within each individual subject was 120–250ms, chosen based on Fig. 2. The topographical group-wise averages are presented on the left side (controls above, EPM1 patients below). On the right side of the topographical average maps, a p-value map is presented to observe areas with statistically significant differences in ERSP or ITC. In the ERSP the significantly different sites are in front of the M1, ipsilateral to TMS and at M1, contralateral to TMS. In the ITC, the frontal, frontocentral, temporal and occipital EEG electrodes indicated significantly higher phase coherence in controls as compared to EPM1 patients. Epilepsy Research 2013 106, 103-112DOI: (10.1016/j.eplepsyres.2013.04.001) Copyright © 2013 Elsevier B.V. Terms and Conditions

Figure 6 ERSP and ITC in the beta band. Comparison of beta band ERSP (panel above) and ITC (panel below) distribution between the groups. The time-window over which the ERSP and ITC were averaged within each individual subject was 25–100ms, chosen based on Fig. 2. The topographical group-wise averages are presented on the left side (controls above, EPM1 patients below). On the right side of the topographical average maps, a p-value map is presented to observe areas with statistically significant differences in ERSP or ITC. In the ERSP the significantly different sites are at and posterior to the M1, both ipsilateral and contralateral to TMS. In the ITC, most of the recorded EEG electrodes indicated significantly higher phase coherence in controls as compared to EPM1 patients. Epilepsy Research 2013 106, 103-112DOI: (10.1016/j.eplepsyres.2013.04.001) Copyright © 2013 Elsevier B.V. Terms and Conditions

Figure 7 ERSP and ITC in the gamma band. Comparison of gamma band ERSP distribution between the groups. The time-window over which the ERSP was averaged within each individual subject was 25–100ms, chosen based on Fig. 2. The topographical group-wise averages are presented on the left side (controls above, EPM1 patients below). On the right side of the topographical average maps, a p-value map is presented to observe areas with statistically significant differences in ERSP. Significant differenced were observed in the vicinity of vertex. No significant differences in the gamma band were observed in ITC, and therefore the topographical maps are omitted. Epilepsy Research 2013 106, 103-112DOI: (10.1016/j.eplepsyres.2013.04.001) Copyright © 2013 Elsevier B.V. Terms and Conditions