Projects at the e-Lab

Neurology and neurosurgery – direct brain recordings

Sometimes the clinical exploration of epilepsy necessitates localizing seizures with direct brain recordings, called i-EEG. In partnership with the Sleep-Wake-Epilepsy Center at Inselspital, we analyze these recordings to better understand cortical dynamics and seizure networks. This requires advanced signal processing and we make use of cutting-edge machine-learning approaches to accelerate our understanding of complex signals.

This figure represent a learned pattern of a discharge in the brain of a patient with focal epilepsy. Artificial intelligence extracted this pattern and countless others from i-EEG signals. 

Clinical research – Pro-ictal states

A major source of suffering for people with epilepsy is the perceived unpredictability of seizures. We discovered that seizures recur during so-called ‘pro-ictal’ states, when the epileptic brain generates abnormally high numbers of epileptic discharges. We next found that these pro-ictal states tend to recur somewhat periodically leading to seizure cycles (see below). 

This set of figures represent fluctuations in the rates of epileptic discharges in the brain of a patient with focal epilepsy, recorded with a chronically implanted i-EEG device. A: two-week recording showing circadian fluctuations in rates of epileptic brain discharges (day 1-5) and multidien increase (day 6-10) culminating in seizures (red dots). B: Average rates of epileptic brain discharges for days at low (green) and high (red) seizure risk. C: Average preferential time of occurrence of epileptic brain discharges. 

Clinical research – seizure cycles

Starting in 2017, we made significant contributions to characterizing ‘seizure cycles’, the fact that epileptic seizures tend to recur with certain regularity in people with epilepsy. Using years-long EEG recordings from over 200 patients implanted with an intracranial EEG device, we found that seizures occur at preferential times (a circadian modulation) and with quasi-periodic seizure-free intervals, a phenomenon for which we coined the term ‘multidien cycles’ (multi-day) of epileptic activity. Thus the lab is pioneering the temporal organisation of epilepsy at time-scales rarely evaluated before, but we have likely only scratched the surface of what neurotechnologies can bring to the management of epilepsy.

This set of figures depict the prevalence (%), strength and pattern of seizure cycles at three timescales. left: circannual, about a year, middle: multidien, about-weekly to about-monthly and right: circadian, about daily. Bottom: Each vector represents a person with epilepsy, the length of the arrow reflects how consistently the seizures occur at a preferential time.

Neuro-engineering – forecasting seizures

In a paradigm shift for the field, we showed that seizure cycles can be extrapolated to forecast seizure over future horizons of a few days. This breakthrough was achieved using sophisticated statistical models called point-process generalized linear models, that can take into account a number of temporal features upon which the momentary risk of seizures may depend. One major variable influencing changes in seizure risk day after day are underlying multidien cycles of epileptic brain activity that can be measured with chronic EEG. This study opened the way to providing personalized probabilistic seizure forecasts, akin to weather forecasts. Previously unimaginable, we can now envision a day when people with epilepsy will be empowered to adjust their own treatment and behavior based on seizure forecasts (video).

Neuroscience – Chronobiology of Epilepsy

In the project ‘Chronobiology of epilepsy’, we launched a series of rodent experiments to accelerate our mechanistic understanding of seizure cycles. Why does epilepsy occur is unclear in most instances. But once epilepsy has started, its defining feature is the recurrence of spontaneous seizures. So, why do seizure occur when they do ? What are the environmental influences ? What systemic or brain state are vulnerable to seizure occurrence ? With the possibility to control firing neurons and ticking circadian clocks, rodent models enable us to accelerate the causal understanding of the chronobiology of epilepsy. The strides we are making would be impossible without a large body of work in animal research that precedes us. This is the necessary basis of serious advances in medicine.

Neuroengineering – EpiOs Project

The Wyss Center for neuro-engineering has developped a minimally invasive device called Epios to enable continuous recording of brain activity while people are at home, work or school. Electrodes placed beneath the scalp will monitor the electrical activity of the brain. A small implanted unit will collect readings from the electrodes and communicate wirelessly with a portable device for storage. The first clinical trial of the electrode device was concluded in 2023 at Inselspital, Bern University Hospital.