A matter of time: analysing time-varying functional brain networks in EEG task-related data

Location: Room No.102, CDS Seminar Hall

Research Seminar

SPEAKER : Nitin Williams
University of Helsinki, Finland

TITLE: A matter of time: analysing time-varying functional brain networks in EEG task-related data

DATE: Monday, April 3, 2017

TIME: 11:00 AM

VENUE: Room 102, CDS/SERC Seminar Hall (First Floor)



Imagine you are seated in a room performing a cognitive task, for e.g. recalling a memory. What processes are occurring in your brain to enable this? Converging evidence suggests that when a task is performed, the brain moves rapidly through a series of functional states, with each state represented by a functional  network of brain regions. Due to its high temporal resolution, EEG (Electroencephalography) is well suited to provide a window to this process. However, there is a lack of analysis methods to reveal these time-varying networks in EEG task-related data.
This talk will present a pipeline we have developed for this purpose. In the pipeline, we determine functional networks from brief time segments (using sparse Multi-Variate Auto-Regressive (MVAR) modelling), group these networks into a small number of functional states (using k-means clustering) and characterise the sequence of states (as a Markov chain). After validating our pipeline on simulated EEG data, we applied it to experimental EEG data from an established cognitive experiment with two conditions, i.e. the oddball task. Using only the description of EEG activity obtained by applying the pipeline, we demonstrate statistically significant discrimination between trials of the two conditions. These results provide powerful proof-of- concept for this approach to modeling the data. This in turn paves the way
for its use in cognitive neuroscience, to test rich hypotheses on sub-second changes in functional networks as a task is being performed.

Bio: Dr. Nitin Williams completed his B.E. in Electronics & Communication Engineering (ECE) from Anna University, India before doing a PhD in Computational Neuroscience from University of Reading, UK. He then completed 4-years of post-doctoral research in the acclaimed MRC Cognition & Brain Sciences Unit, Cambridge, UK. He is currently funded by the flagship Human Brain Project (HBP), on a post-doctoral project to infer the brain-wide pattern of functional interactions in the human brain. This is being done in University of Helsinki, Finland. He is particularly interested in advancing understanding of human brain function by developing methods to harness the potential of EEG/MEG. He is also interested in building biophysical models to emulate EEG/MEG data, thereby facilitating a mechanistic understanding of cognitive function in both health and disease.