TY  - JOUR
A1  - Beim Graben, Peter
T1  - Symbolic resonance analysis of event-related potentials distinguishes different physiological processes
Y1  - 2005
SN  - 0898-929X
ER  - 
TY  - JOUR
A1  - Beim Graben, Peter
A1  - Frisch, Stefan
A1  - Fink, A.
A1  - Saddy, Douglas
A1  - Kurths, Jürgen
T1  - Topographic voltage and coherence mapping of brain potentials by means of the symbolic resonance analysis
N2  - We apply the recently developed symbolic resonance analysis to electroencephalographic measurements of event- related brain potentials (ERPs) in a language processing experiment by using a three-symbol static encoding with varying thresholds for analyzing the ERP epochs, followed by a spin-flip transformation as a nonlinear filter. We compute an estimator of the signal-to-noise ratio (SNR) for the symbolic dynamics measuring the coherence of threshold-crossing events. Hence, we utilize the inherent noise of the EEG for sweeping the underlying ERP components beyond the encoding thresholds. Plotting the SNR computed within the time window of a particular ERP component (the N400) against the encoding thresholds, we find different resonance curves for the experimental conditions. The maximal differences of the SNR lead to the estimation of optimal encoding thresholds. We show that topographic brain maps of the optimal threshold voltages and of their associated coherence differences are able to dissociate the underlying physiological processes, while corresponding maps gained from the customary voltage averaging technique are unable to do so
Y1  - 2005
SN  - 1539-3755
ER  - 
TY  - JOUR
A1  - Drenhaus, Heiner
A1  - Beim Graben, Peter
A1  - Saddy, Douglas
A1  - Frisch, Stefan
T1  - On the processing of negative polarity constructions revealed by the symbolic resonance analysis
Y1  - 2005
SN  - 0898-929X
ER  - 
TY  - JOUR
A1  - Frisch, Stefan
A1  - Beim Graben, Peter
T1  - Finding needles in haystacks : Symbolic resonance analysis of event-related potentials unveils different processing demands
N2  - Previous ERP studies have found an N400-P600 pattern in sentences in which the number of arguments does not match the number of arguments that the verb can take. In the present study, we elaborate on this question by investigating whether the case of the mismatching object argument in German (accusative/direct object versus dative/ indirect object) affects processing differently. In general, both types of mismatches elicited a biphasic N400 P600 response in the ERP. However, traditional voltage average analysis was unable to reveal differences between the two mismatching conditions, that is, between a mismatching accusative versus dative. Therefore, we employed a recently developed method on ER-P data analysis, the symbolic resonance analysis (SRA), where EEG epochs are symbolically encoded in sequences of three symbols depending on a given parameter, the encoding threshold. We found a larger proportion of threshold crossing events with negative polarity in the N400 time window for a mismatching dative argument compared to a mismatching accusative argument. By contrast, the proportion of threshold crossing events with positive polarity was smaller for dative in the P600 time window. We argue that this difference is due to the phenomenon of "free dative" in German. This result also shows that the SRA provides a useful tool for revealing ERP differences that cannot be discovered using the traditional voltage average analysis. (c) 2005 Elsevier B.V. All rights reserved
Y1  - 2005
ER  -