Event Abstract

Mechanisms underlying different onset patterns of focal seizures

  • 1 Newcastle University, School of Computing Science, United Kingdom

Focal seizures typically begin with an electrographic onset pattern that is highly stereotyped in individual patients. Qualitative classifications of these onset patterns describe two frequently occurring waveforms – low amplitude fast oscillations (LAF), or high amplitude spikes (HAS). Interestingly, only the former of the patterns is associated with a good surgical outcome. Given the importance of this clinical distinction, we therefore explored whether these two patterns arise from fundamentally different spatio-temporal dynamics. We used a previously established computational model of neocortical tissue, and validated it as an adequate model using clinical recordings of focal seizures. Using this model we then investigated the possible mechanisms underlying the different focal seizure onset patterns. We show that the two patterns are associated with different mechanisms at the spatial scale of a single ECoG electrode. The LAF onset is initiated by independent patches of localised activity, which slowly invade the surrounding tissue and coalesce over time (see Fig. 1A). In contrast, the HAS onset is a global, systemic transition to a coexisting seizure state triggered by a local event (see Fig. 1B). We find that such a global transition is enabled by an increase in excitability of the surrounding tissue, essentially creating a seizure supporting surrounding. In our simulations, the difference in surrounding tissue excitability also offers a simple explanation of the clinically observed difference in surgical outcomes. Finally, we demonstrate how changes in tissue excitability could be elucidated in principle using active stimulation. We conclude that the excitability of the tissue surrounding the seizure core plays a determining role in the seizure onset pattern, as well as in the surgical outcome.

Figure 1

Keywords: Epilepsy, neural mass model, Seizures, Seizure onset pattern, cortical excitability

Conference: Neuroinformatics 2016, Reading, United Kingdom, 3 Sep - 4 Sep, 2016.

Presentation Type: Investigator presentations

Topic: Brain disorders

Citation: Wang Y (2016). Mechanisms underlying different onset patterns of focal seizures. Front. Neuroinform. Conference Abstract: Neuroinformatics 2016. doi: 10.3389/conf.fninf.2016.20.00016

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Received: 26 Apr 2016; Published Online: 18 Jul 2016.

* Correspondence: Dr. Yujiang Wang, Newcastle University, School of Computing Science, Newcastle upon Tyne, NE1 7RU, United Kingdom, Yujiang.Wang@newcastle.ac.uk

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