The development of a novel tool promises to greatly enhance researchers’ understanding of epileptic seizures.
Epileptic activity in humans can be studied by focusing on the identification and localisation of the brain sources and networks, specifically, intrinsic connectivity networks [ICN], which are emerging as a fundamental aspect of brain function in health and disease.
However, as with other studies utilising fMRI, there are limitations – while some ICN appear to be specifically involved in, or affected by, epileptic activity, this has not been studied systematically enough and there is a need to improve the analysis and interpretation of functional MRI data. This can be done by addressing one of fMRI’s main limitations: a subjective element in terms of localisation and overall interpretation of sometimes complex maps; and by taking advantage of new knowledge on functional brain networks, in the form of ICN.
A BRC-supported study team from UCL, in collaboration with colleagues in Budapest, created an entirely new software tool - ICN_Atlas, tested and validated it on two large datasets from the public domain; and demonstrated its scientific potential using an in-house dataset acquired in an epilepsy patient who had repeated seizures during a functional MRI scan. Such data is rare and very valuable because of the vast amount of unique information it contains on how the entire brain is affected prior, during and after seizures.
Professor Louis Lemieux, corresponding author on the paper in Neuroimage, said: “ICN_Atlas is based on the concept of ‘atlasing’: fMRI maps of interest are projected onto an atlas that contains the ICN and statistics are calculated that quantify the degree of involvement of each ICN in the fMRI map. For example, the method can reveal whether a particular ICN, such as the Default Mode Network for example, and to what degree, is involved during epileptic seizures.”
This practical, easy to use solution to an old problem, combined with a new tool for the interpretation of any fMRI activation pattern in relation to ICN, is of significant value. Furthermore, ICN_Atlas is applicable to all fMRI studies: cognitive and of disease processes and therefore has the potential to change how fMRI data is interpreted in all its applications.
Prof Lemieux said: “We are using the tool to increase our understanding of interaction between epileptic brain activity and the neural networks that sustain normal brain function. We hope that this will help us better characterise seizure spread and understand how this affects brain function.”
