Abnormal ERD/ERS but Unaffected BOLD Response in Patients with Unverricht–Lundborg Disease During Index Extension: A Simultaneous EEG-fMRI Study
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Electrophysiological studies indicate that Unverricht–Lundborg’s disease (ULD), the most common form of progressive myoclonus epilepsy in Europe, is characterized by the involvement of multiple cortical regions in degenerative changes that lead to enhanced excitation and deficient inhibition. We searched for the haemodynamic correlates of these effects using functional MRI (fMRI) of self-paced index extensions, a well-accepted task highlighting significant differences. EEG and fMRI were simultaneously acquired in 11 ULD patients and 16 controls, performing the index extensions individually (event-related task) as well as repetitively (block task). ERD/ERS analysis was performed for the EEG data in the alpha and beta bands. fMRI time-series were analyzed using the traditional general linear model, as well as with an assumption-free approach, and by means of cross-region correlations representing functional connectivity. In line with the existing literature, ULD patients had enhanced desynchronization in the alpha band and reduced post-movement synchronization in the beta band. By contrast, fMRI did not reveal any difference between the two groups; there were no activation intensity, latency or extent effects, no significant engagement of additional regions, and no changes to functional connectivity. We conclude that, so long as the patients are executing a task which does not induce obvious action myoclonus, the hypothesized abnormalities in pyramidal neuron and interneuron dynamics are relatively subtle, embodied in processes which are not metabolically-demanding and take place at a time-scale invisible to fMRI.
KeywordsUnverricht–Lundborg disease ERD/ERS analysis Simultaneous EEG-fMRI
This research has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement HEALTH-F5-2008-201076. The authors are grateful to Lucia Salvatoni for outstanding technical assistance during EEG data acquisition. The authors would also like to thank two anonymous reviewers for the insightful feedback they provided on an earlier draft.
- Hoshi E, Tanji J (2007) Distinctions between dorsal and ventral premotor areas: anatomical connectivity and functional properties. Curr Opin Neurobiol 17(2):234–242 (Epub 20 Feb. Review)Google Scholar
- Parkes LM, Bastiaansen MC, Norris DG (2005) Combining EEG and fMRI to investigate the post-movement beta rebound. Neuroimage 29(3):685–696 (Epub 19 Oct)Google Scholar
- Pennacchio LA, Lehesjoki AE, Stone NE, Willour VL, Virtaneva K, Miao J, D’Amato E, Ramirez L, Faham M, Koskiniemi M, Warrington JA, Norio R, de la Chapelle A, Cox DR, Myers RM (1996) Mutations in the gene encoding cystatin B in progressive myoclonus epilepsy (EPM1). Science 271(5256):1731–1734PubMedCrossRefGoogle Scholar
- Virtaneva K, D’Amato E, Miao J, Koskiniemi M, Norio R, Avanzini G, Franceschetti S, Michelucci R, Tassinari CA, Omer S, Pennacchio LA, Myers RM, Dieguez-Lucena JL, Krahe R, de la Chapelle A, Lehesjoki AE (1997) Unstable minisatellite expansion causing recessively inherited myoclonus epilepsy, EPM1. Nat Genet 15(4):393–396PubMedCrossRefGoogle Scholar
- Visani E, Minati L, Canafoglia L, Gilioli I, Salvatoni L, Varotto G, Fazio P, Aquino D, Bruzzone MG, Franceschetti S, Panzica F (2010) Simultaneous EEG-fMRI in patients with Unverricht–Lundborg disease: event-related desynchronization/synchronization and hemodynamic response analysis. Comput Intell Neurosci 164278. doi: 10.1155/2010/164278