Functional connectivity in the brain
We are investigating changes in functional connectivity of the brain associated with epilepsy.
Functional connectivity is a measure of how regions of the brain interact with each other. Brain activation can be mapped non-invasively with functional MRI (fMRI).There are various scales at which one can measure functional connectivity. For example seeded connectivity analysis examines correlations in functional MRI signal between pre-defined regions of interest. This can be extended to the whole brain by examining correlations between all possible pairs of regions throughout the brain. An alternative approach is regional homogeneity analysis, which determines local connectivity (correlations between a voxel and its immediate neighbours). We are also actively developing new methods that can improve the spatial and temporal resolution of functional connectivity measurements.
We have made some important discoveries. For example, we have found that there are common brain areas with abnormal local connectivity in patients with focal epilepsy, despite lesion location varying across individuals. We have also discovered that in some cases a single very small brain lesion can cause widespread change in functional connectivity throughout the brain.
Omidvarnia, A., Pedersen, M., Walz, J.M., Vaughan, D.N., Abbott, D.F., Jackson, G.D., 2016. Dynamic regional phase synchrony (DRePS). Hum. Brain Mapp. 37, 1970–1985. doi:10.1002/hbm.23151
Warren, A.E.L., Abbott, D.F., Vaughan, D.N., Jackson, G.D., Archer, J.S., 2016. Abnormal cognitive network interactions in Lennox-Gastaut syndrome: A potential mechanism of epileptic encephalopathy. Epilepsia 57, 812–822. doi:10.1111/epi.13342
Sethi, M., Pedersen, M., Jackson, G.D., 2016. Polymicrogyric Cortex may Predispose to Seizures via Abnormal Network Topology: An fMRI Connectomics Study. Epilepsia 57, e64–e68. doi:10.1111/epi.13304
Pedersen, M., Omidvarnia, A.H., Walz, J.M., Jackson, G.D., 2015. Increased segregation of brain networks in focal epilepsy: An fMRI graph theory finding. NeuroImage: Clinical 8, 536–542. doi:10.1016/j.nicl.2015.05.009
Pedersen, M., Curwood, E.K., Archer, J.S., Abbott, D.F., Jackson, G.D., 2015. Brain regions with abnormal network properties in severe epilepsy of Lennox-Gastaut phenotype: Multivariate analysis of task-free fMRI. Epilepsia 56, 1767–1773. doi:10.1111/epi.13135
Tailby, C., Masterton, R.A.J., Huang, J.Y., Jackson, G.D., Abbott, D.F., 2015. Resting state functional connectivity changes induced by prior brain state are not network specific. NeuroImage 106, 428–440. doi:10.1016/j.neuroimage.2014.11.037
Pedersen, M., Curwood, E.K., Vaughan, D.N., Omidvarnia, A.H., Jackson, G.D., 2015. Abnormal Brain Areas Common to the Focal Epilepsies: Multivariate Pattern Analysis of fMRI. Brain Connectivity 6, 208–215. doi:10.1089/brain.2015.0367
Masterton, R.A., Carney, P.W., Jackson, G.D., 2012. Cortical and thalamic resting-state functional connectivity is altered in childhood absence epilepsy. Epilepsy Research 99, 327–334. doi:10.1016/j.eplepsyres.2011.12.014
Waites, A.B., Briellmann, R.S., Saling, M.M., Abbott, D.F., Jackson, G.D., 2006. Functional connectivity networks are disrupted in left temporal lobe epilepsy. Annals of Neurology 59, 335–343. doi:10.1002/ana.20733
Waites, A.B., Stanislavsky, A., Abbott, D.F., Jackson, G.D., 2005. Effect of prior cognitive state on resting state networks measured with functional connectivity. Human Brain Mapping 24, 59–68. doi:10.1002/hbm.20069