Frequency domain equivalence between potentials and currents using LORETA.
Analyzing the preferences of brain regions to oscillate at specific frequencies gives important functional information. Application of discrete inverse solutions for the EEG/MEG inverse problem in the frequency domain usually involves the use of many current sources (sometimes 10(4) or more) restricted to gray matter points, as the solution space for the possible generators. This number can progressively increase with the level of detail of the MRI when it is used in co-registration with EEG/MEG. However, the computation of the Fourier transform to all these sources is computationally intensive. We illustrate with a simple example how this procedure can be simplified by applying the Fourier transform to the signals in the sensors using a popular inverse method (LORETA). We also suggest how the search space of current sources at specific frequencies of oscillation can be limited to some regions constrained by other technologies such as fMRI, PET and SPECT.
Gomez
J F
JF
Bay Pines VA Medical Center, Bay Pines, FL 33744, USA.
Thatcher
R W
RW
D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D005583:Fourier Analysis; D006801:Humans; D016014:Linear Models; D015225:Magnetoencephalography; D008959:Models, Neurological