Exact low resolution brain electromagnetic tomography or eLORETA is a linear inverse solution method that can be applied to high time resolution, scalp EEG recordings to compute the three-dimensional distribution of electric cortical activity at any number of locations in the brain with no localization error to point sources under ideal (noise-free) conditions [28]–[30]. In addition, measures of “similarity” between any pair of intracranial signals can be obtained as an index of physiological “lagged connectivity” between the respective sites. This novel connectivity measure is resistant to non-physiological artifacts, in particular volume conduction and low spatial resolution that usually affect other connectivity indices [26], [27]. Furthermore, it can be applied to filtered data, thus giving a frequency decomposition of brain connectivity [30]–[32].
