Statistical analysis tool for time/frequency state spaces.

Lead Research Organisation: University of Glasgow
Department Name: College of Medical, Veterinary, Life Sci

Abstract

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Technical Summary

In recent years, new ways to investigate EEG recordings have emerged. In particular, Event Related Spectral Perturbations (ERSP) and Inter-Trial phase Coherence (ITC) have become the standard to characterize the time-frequency decompositions of signals from electrodes or components (e.g. from independent component analysis). Yet, no adequate statistical tools are available to investigate all the dimensions of ERSP and ITC at once: all electrodes/components, time frames, frequencies, amplitude and phase. Our project will provide a freely distributed toolbox allowing such comprehensive analyses. The toolbox will be based on mass-univariate robust statistics and validated multiple comparison correction procedures. This tool will improve significantly data analysis standards. Having such tool will also expand the spectrum of possible experiments, which are currently often limited to binary designs (e.g. condition A vs. condition B), simply because there is no good way to analyse more complex experiments. In turn, this will lead to an increase in our understanding of biological and psychological phenomena. The toolbox will be distributed along with datasets used to validate our methods so that user can familiarise themselves with the new techniques and other research groups can use them to compare methods.

Planned Impact

Our new tool will benefit public and private sector researchers using magneto- and electro-encephalography data analysis. We anticipate five main outcomes from our work:
[1] Researchers will not have to limit their analyses to a-priori interesting features. Instead, they will be able to exploit the full data space.
[2] Our tool will effectively control the negative consequences of exploring a full data space: false positive will be minimized without sacrificing power.
[3] Researchers will have the possibility to analyse more complex designs that cannot be managed by current toolboxes. This should enable researchers to use more sophisticated experimental designs and ask new questions about brain activity.
[4] The free availability of datasets from our own simulations will be useful for validation of methods by other research groups or for people to familiarise themselves with the new techniques.
[5] Overall, our work will contribute to the on-going paradigm shift in MEEG: away from simple group analyses of few regions of interests, and towards higher standards, including comprehensive analyses of single-subject and group data.

Publications

10 25 50
 
Description The electroencephalogram, or EEG, consists of fluctuations in brain electrical activity that can be measured whilst people are doing cognitive tasks (e.g. seeing objects, reading, listening). Recordings consist in time-series and are collected via multiple electrodes at the surface of the skull. Mathematical operations allow decomposing those recordings into more easy interpretable signals to examine, for instance, different frequencies (e.g. slow and fast fluctuations of the signal) or components (the likely cerebral origins making up the recorded signal). In this research we developed tools / software that allow analysing the entire data space simultaneously, as for instance all electrodes on the scalp for all time points collected and throughout all temporal frequencies.

Concretely, we have written code for methods (and validated them through simulations) that allow researchers to perform many statistical tests on the data (that is for the whole data space), while ensuring the results are not just due to chance (a problem known as control of family-wise error rate). These tools are coded in a popular mathematical language/software (MATLAB), are freely available, and are also distributed through another software commonly used to analyse EEG data (EEGLAB).
Exploitation Route The tools developed are freely available under GPL. This implies that the research outcomes can be (1) used by anyone and (2) incorporated and developed for any other purpose than initially intended.
In addition of making sure that this work can be reused, it has been promoted via publications and via the participation of the applicants to workshops and conferences. Future specialist workshops are planned to present the tools and software developed.
Sectors Digital/Communication/Information Technologies (including Software),Healthcare,Pharmaceuticals and Medical Biotechnology

URL https://gforge.dcn.ed.ac.uk/gf/project/limo_eeg/
 
Title LIMO EEG 
Description LIMO EEG is an open source Matlab toolbox for the linear modelling of EEG data. In the course of the grant we released a new version of the toolbox, and are working on the next release, including latest innovations developed through the grant. 
Type Of Technology Software 
Year Produced 2013 
Open Source License? Yes  
Impact This toolbox is contributing to the slow improvement in the quality of EEG and MEG data analyses. We hope to see benefits in academic and applied research, including clinical research. 
URL https://gforge.dcn.ed.ac.uk/gf/project/limo_eeg/
 
Description APS ERP workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Attendees learned how to better analyse their data, and engaged in discussions afterwards. Attendees left with new tools and ideas to apply to their work.

After my workshop, I started a new collaboration with a group based in Marseille. Several attendees have been using the tools I taught in their research - hopefully improving the quality of their research in the process.
Year(s) Of Engagement Activity 2013
 
Description EEGLAB workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact My workshop about robust statistics applied to EEG/ERP analyses sparkled a lot of long and passionate discussions that day and the following days.

The workshop triggered increased interest in the Matlab toolbox developed as part of the grant, as well as requests for help and input on data analysis from labs around the world.
Year(s) Of Engagement Activity 2013
 
Description Fribourg EEG workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact Attendees at this two day workshop learnt how to analysis their data using the tools developed in the context of the grant. The workshop triggered many discussions about practical and fundamental aspects.

After the workshop, attendees engaged with the tools and applied them to their own research.
Year(s) Of Engagement Activity 2014