Synchronization Implies Seizure or Seizure Implies Synchronization?
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Epileptic seizures are considered as abnormally hypersynchronous neuronal activities of the brain. The question is “Do hypersynchronous neuronal activities in a brain region lead to seizure or the hypersynchronous activities take place due to the progression of the seizure?” We have examined the ECoG signals of 21 epileptic patients consisting of 87 focal-onset seizures by three different measures namely, phase synchronization, amplitude correlation and simultaneous occurrence of peaks and troughs. Each of the measures indicates that for a majority of the focal-onset seizures, synchronization or correlation or simultaneity occurs towards the end of the seizure or even after the offset rather than at the onset or in the beginning or during the progression of the seizure. We have also briefly discussed about a couple of synchronization dependent seizure termination mechanisms. Our conclusion is synchronization is an effect rather than the cause of a significant number of pharmacologically intractable focal-onset seizures. Since all the seizures that we have tested belong to the pharmacologically intractable class, their termination through more coherent neuronal activities may lead to new and effective ways of discovery and testing of drugs.
KeywordsElectrocorticography (ECoG) Focal epilepsy Hilbert phase synchronization Amplitude correlation Peaks and troughs detection Seizure termination dynamics
This work has been supported by an internal research grant of the Indian Statistical Institute given to the Systems Science and Informatics Unit. We are thankful to the Freiburg Seizure Prediction Project for making their epileptic ECoG data available to the research community all over the world, which we eventually accessed and worked on. We would also like to thank the three anonymous referees whose suggestions resulted in improvements in the paper.
- Dauwels J, Eskandar E, Cash S (2009) Localization of seizure onset area from intracranial non-seizure EEG by exploiting locally enhanced synchrony. Proc IEEE Eng Med Biol Soc 3:2180–2183Google Scholar
- Freiburg data (2008) available from the Freiburg seizure detection project, Albert-Ludwig-Universitat, Freiburg, Germany. https://epilepsy.uni-freiburg.de/. 2008
- Kandel ER, Jessel TM, Schwartz JH (2000) Principles of neural science, 4th edn. McGraw Hill, New YorkGoogle Scholar
- Penfield W, Jasper H (1954) Epilepsy and functional anatomy of the human brain. Little-Brown, BostonGoogle Scholar
- Rummel C, Goodfellow M, Gast H, Hauf M, Amor F, Stibal A, Mariani L, Wiest R, Schindler K 2012 A systems-level approach to human epileptic seizures. Neuroinformatics. doi: 10.1007/s12021-012-9161-2. (to appear)
- Schevon CA, Weiss SA, McKhann Jr G, Goodman RR, Yuste R, Emerson RG, Trevelyan AJ (2012) Evidence of an inhibitory restraint of seizure activity in humans. Nat Commun 3: 1060 http://www.nature.com/ncomms/journal/v3/n9/abs/ncomms2056.html
- Somjen GG, Tombaugh GC (1998) pH modulation of neuronal excitability and central nervous system functions. In: Kalia K, Ransom BR (eds) pH and brain function. Wiley-Liss, New York, pp 373–393Google Scholar