Dipolar source modeling of the P300 event‐related potential after somatosensory stimulation

Abstract

The cerebral generators of the P300 potential evoked by somatosensory stimuli were investigated. Event-related potentials elicited by an oddball paradigm were recorded in 15 healthy subjects by 19 scalp electrodes. Nontarget and target electric stimuli were delivered on the anterior surface of the left elbow and of the wrist, respectively. Target traces showed an N140 potential followed by a widely distributed P300 response. Dipolar source modeling of target traces resulted in a six-dipole model. In the earlier latency range (up to 200 ms), one dipole in the contralateral perirolandic region and two dipoles in the parasylvian cortex of both hemispheres were activated. Two dipolar sources located bilaterally in the medial temporal region (MTR) showed their maximal activity at the P300 latency. Finally, a dipole in the contralateral frontal lobe was activated both at the latency of the N140 response and after 200 ms. It was found that two symmetrical MTR sources and a frontal dipole contributed to P300 generation.

How Do Brain Areas Communicate During the Processing of Noxious Stimuli? An Analysis of Laser-Evoked Event-Related Potentials Using the Granger Causality Index

“…The anatomical accurateness of the dipole localizations of the BESA approach should not be overestimated due to the intrinsic limitations of the approach (Valeriani et al 2001). A possible way to overcome these limitations might be the use of fMRI to provide anatomical constraints for the dipole analysis.…”

“…Finally, a dipolar source modeling was performed on the grand average of the LEPs using brain electrical source analysis (BESA; Scherg 1990), also known as the spatiotemporal source method (Valeriani et al 2001). It should be mentioned that we use the term "dipole generator" for the BESA results to distinguish it from the terms "sources" and "sinks" of the GCI analysis (that represent distinct electrodes).…”

“…BESA can also be used to verify whether a hypothesized dipolar model accounts for the recorded magnetic fields or potentials (i.e., LEPs). Here, we used a sequential analysis as described in detail by Valeriani et al (2001). For this analysis, the entire time interval was divided into segments, similarly to those for the tvGCI analysis.…”

“…In a second step, the analysis was performed on the averaged LEP of each individual to provide information on the variance of spatial localization. Although the advantage of this approach should not be overestimated due to intrinsic limitations of the approach (for review, see Valeriani et al 2001), it provides useful information on the possible cerebral sources and voltage fields produced by these sources at each electrode site (e.g., Cruccu et al 2003;Opsommer et al 2001).…”

Localizing P300 Generators in Visual Target and Distractor Processing: A Combined Event-Related Potential and Functional Magnetic Resonance Imaging Study

“…Compared with intracranial recordings of P300-like signals, the source analysis of scalp electroencephalography (EEG) or magnetencephalography data has the advantage that it can be applied and replicated in large numbers of healthy subjects and potentially covers the entire brain. Several eventrelated potential (ERP) studies have tried to localize the sources of the P3b component in the auditory, visual, and somatosensory modalities (Mecklinger and Ullsperger, 1995;Tarkka et al, 1995Tarkka et al, , 1996Hegerl and Frodl-Bauch, 1997;Anderer et al, 1998;Mecklinger et al, 1998, Tarkka andStokic, 1998;Yamazaki et al, 2000Yamazaki et al, , 2001Jentzsch and Sommer, 2001;Valeriani et al, 2001;Dien et al, 2003). These studies had inconsistent results, which might be attributable to the ''inverse problem" posed by the infinite number of current source distributions that can explain the scalp ERP data.…”