OBJECTIVE: We tried to determine the error range of dipole modeling for EEG spikes originating from various clinically important sources by a simulation study employing a realistic head model. The computed error range was also compared with the degree of disturbance of dipole modeling caused by adding background activity to the spike. METHODS: The scalp fields generated by temporal, frontal and rolandic epileptic sources with spatial extent were simulated, and the corresponding 3-dimensional maps of residual variance (RV) were built by computing the RV for a single dipole at each point on a fine imaginary grid in the brain. Single dipole modeling was also performed for the simulated scalp fields after adding real background activity. RESULTS: The brain volume corresponding to a small RV was compact for the frontal sources and the lateral and baso-mesial temporal sources, and large for the anterior and baso-lateral temporal sources. The distribution of dipoles estimated for spikes contaminated with background corresponded to that of the volume of small RV and to spike-amplitude. Estimates were improved by employing inferior temporal electrodes. CONCLUSIONS: When evaluating dipole models of epileptic spikes, error ranges can be estimated and they vary considerably from region to region. SIGNIFICANCE: This study illustrates the variability of the error in dipole modeling of epileptic spikes. This variability is important when considering the clinical interpretation of modeling results.
OBJECTIVE: We tried to determine the error range of dipole modeling for EEG spikes originating from various clinically important sources by a simulation study employing a realistic head model. The computed error range was also compared with the degree of disturbance of dipole modeling caused by adding background activity to the spike. METHODS: The scalp fields generated by temporal, frontal and rolandic epileptic sources with spatial extent were simulated, and the corresponding 3-dimensional maps of residual variance (RV) were built by computing the RV for a single dipole at each point on a fine imaginary grid in the brain. Single dipole modeling was also performed for the simulated scalp fields after adding real background activity. RESULTS: The brain volume corresponding to a small RV was compact for the frontal sources and the lateral and baso-mesial temporal sources, and large for the anterior and baso-lateral temporal sources. The distribution of dipoles estimated for spikes contaminated with background corresponded to that of the volume of small RV and to spike-amplitude. Estimates were improved by employing inferior temporal electrodes. CONCLUSIONS: When evaluating dipole models of epileptic spikes, error ranges can be estimated and they vary considerably from region to region. SIGNIFICANCE: This study illustrates the variability of the error in dipole modeling of epileptic spikes. This variability is important when considering the clinical interpretation of modeling results.
Authors: Deirel Paz-Linares; Mayrim Vega-Hernández; Pedro A Rojas-López; Pedro A Valdés-Hernández; Eduardo Martínez-Montes; Pedro A Valdés-Sosa Journal: Front Neurosci Date: 2017-11-16 Impact factor: 4.677