A new strategy involving multiple cognitive paradigms demonstrates that ERP components are determined by the superposition of oscillatory responses.
OBJECTIVE
The goal of the present paper was to study the contribution of the delta and theta responses to two components of the event-related potential (ERP) waveform, the N200 and P300, which were recorded from 3 topographical sites of the brain.


METHODS
This contribution was studied using a set of systematically varying experimental paradigms. Such a strategy enabled the demonstration of the variations in the event-related potentials and the event-related oscillations as task conditions and respective cognitive operations systematically changed. The study employed easy oddball, hard oddball, mismatch negativity and single stimulus paradigms and it was conducted on 42 healthy adults (age range 19-30 years, 26 females, 16 males) from the university student population. Data were analyzed with electrophysiological (selective averaging, amplitude frequency characteristics, digital filtering) and statistical methods (analysis of variance, multivariate step-down regression).


RESULTS
The data showed that the morphology of the ERP components for different experimental paradigms represented a specific pattern of superposition of the delta and theta oscillatory responses.


CONCLUSIONS
The cognitive correlates of the oscillatory responses were discussed and the results were evaluated on the basis of the superposition principle and the theory of oscillatory neural assemblies.
Karakaş
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Department of Experimental Psychology, Hacettepe University, Beytepe 06532, Ankara, Turkey. skarakas@hacettepe.edu.tr
Erzengin
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Başar
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D000161:Acoustic Stimulation; D000328:Adult; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology