Theta EEG source localization using LORETA in partial epilepsy patients with and without medication

Abstract

Objective. To investigate and localize the sources of spontaneous, scalp-recorded theta activity in patients with partial epilepsy (PE).Methods. 9 patients with beginning, untreated PE (Group1), 31 patients with already treated PE (Group2), and 14 healthy persons were investigated by means of spectral analysis and LORETA, low resolution electromagnetic tomography (1 Hz very narrow band analysis, age-adjusted, Z-scored values). The frequency of main interest was 4 to 8 Hz Results. Group analysis. Group1 displayed bilateral theta maxima in the temporal theta area (TTA), parietal theta area (PTA), and frontal theta area (FTA). In Group2, theta activity increased all over the scalp as compared to the normative mean (Z=0) and also to Group1. Maximum activity was found in the TTA, PTA, and FTA. However, in the PTA and FTA the centers of the abnormality shifted towards the medial cortex. Individual analysis: all the patients showed preferential activation (maximum Zvalues) within one of the three theta areas. 2Conclusion. EEG activity in the theta band is increased in anatomically meaningful patterns in PE patients, which differs from the anatomical distribution of theta in healthy persons.Significance. The findings contribute to our understanding of the sources of theta rhythms and the pathophysiology of PE.

Spectral Parameters Modulation and Source Localization of Blink-Related Alpha and Low-Beta Oscillations Differentiate Minimally Conscious State from Vegetative State/Unresponsive Wakefulness Syndrome

“…Cortical sources of electrical activity in low-alpha, high-alpha and low-beta bands were estimated for each trial in the 500 ms time-window encompassing the BRO peak (50 ms to 550 ms after T0) by means of sLORETA [29], [43], which has been widely used to localize cortical current sources with set-ups consisting of as few as 19 electrodes [20], [44], [45].…”

Cortical source of blink-related delta oscillations and their correlation with levels of consciousness

“…To determine the sources of electrical activity in correspondence with EEG responses to blink events, the standardized Low Resolution Electromagnetic Tomography (sLORETA) method [Pascual-Marqui et al, 1994, 2002 was employed. sLORETA has been widely used to localize sources of currents with set-ups consisting of as few as 19 electrodes [Pascual-Marqui et al, 2002], reaching sublobar accuracy [Clemens et al, 2010].…”

Functional Neural Network Connectivity in Myalgic Encephalomyelitis

“…Accurate estimations of the intracranial activity can be achieved with application of inverse methods such as low-resolution electromagnetic tomography (LORETA) and more recent iterations: standardized LORETA (sLORETA) and exact LORETA (eLORETA; Pascual-Marqui, Esslen, Kochi, & Lehmann, 2002;Pascual-Marqui, Lehmann, et al, 2011;Pascual-Marqui, Michel, & Lehmann, 1994). These methods, which allow cross-validation through voxel by voxel coregistration to PET, SPECT, fMRI for matching data to standard coordinate systems, have been used to characterize spatiotemporal dynamics in patients with a wide variety of clinical conditions such as Alzheimer's disease (Babiloni, Binetti, et al, 2004;Babiloni, Cassetta, et al, 2006;Canuet et al, 2012;Gianotti, Künig, Faber, et al, 2008;Gianotti, Künig, Lehmann, et al, 2007), mild cognitive impairment (Babiloni, Carducci, et al, 2013;Babiloni, Del Percio, et al, 2014;Babiloni, Frisoni, et al, 2006), other dementias (Nishida et al, 2011;Styliadis, Kartsidis, Paraskevopoulos, Ioannides, & Bamidis, 2015), epilepsy (Besenyei et al, 2012;Canuet et al, 2011;Clemens et al, 2010), Parkinson's disease (Babiloni et al, 2011;Moazami-Goudarzi, Sarnthein, Michels, Moukhtieva, & Jeanmonod, 2008), multiple sclerosis (Papageorgiou et al, 2007), chronic fatigue syndrome (Sherlin et al, 2007), congestive heart failure (Vecchio et al, 2015), obstructive sleep apnea (Toth, Faludi, Wackermann, Czopf, & Kondakor, 2009), migraine (Clemens et al, 2008), tinnitus (Vanneste et al, 2010), and Down's syndrome (Velikova et al, 2011). LORETA has also been used to investigate neuropsychiatric conditions including locked-in syndrome (Babiloni et al, 2010), anhedonia (Wacker, Dillon, & Pizzagalli, 2009), obsessive-compulsive disorder…”