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Updated: Aug 20, 2026
Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns
Published on: May 12, 2019
Intracerebral P3-like waveforms and the length of the stimulus-response interval in a visual oddball paradigm
Robert Roman1, Milan Brázdil, Pavel Jurák
1Department of Physiology, Medical Faculty, Masaryk University, Komenského nám. 2 662 43 Brno, Czech Republic. roman@med.muni.cz
Objective:
This study investigated the possible linkage of intracerebrally recorded P3-like waveforms to the processes induced by stimulus perception or motor response formation.
Methods:
Event-related potentials were recorded from 560 cerebral sites in 17 patients suffering from intractable epilepsy during visual oddball task. Potentials evoked by the target stimuli were sorted according to button-pressing response times, and the P3 waveform was analyzed both in stimulus-locked and response-locked averages, which were separately averaged for fast and slow responses.
Results:
P3-like waveforms were identified in 180 sites in 17 patients. Three different types of P3-like waveforms, diffusely distributed within the brain, were found: (1) time-locked to the stimulus (30 sites in 11 patients); (2) time-locked to the motor response (52 sites in 13 patients); and (3) with ambiguous time relationship to stimulus and motor response (98 sites in 16 patients).
Conclusions:
The intracerebral P3-like waveform could represent different processes involved in performing active oddball tasks. Therefore, our results support the hypothesis that the P3 waveform registered by surface electrodes could be a heterogeneous phenomenon.
Significance:
These results provide evidence that the P3 waveform is not only related to stimulus processing, which differs from what has been generally claimed in the literature.
