Visual stimulation is frequently employed in electroencephalographic (EEG) research. However, despite its widespread use, no studies have thoroughly evaluated how the morphology of the visual event-related potentials (ERPs) varies according to the spatial location of stimuli. Hence, the purpose of this study was to perform a detailed retinotopic mapping of visual ERPs. We recorded EEG activity while participants were visually stimulated with 60 pattern-reversing checkerboards placed at different polar angles and eccentricities. Our results show five pattern-reversal ERP components. C1 and C2 components inverted polarity between the upper and lower hemifields. P1 and N1 showed higher amplitudes and shorter latencies to stimuli located in the contralateral lower quadrant. In contrast, P2 amplitude was enhanced and its latency was reduced by stimuli presented in the periphery of the upper hemifield. The retinotopic maps presented here could serve as a guide for selecting optimal visuo-spatial locations in future ERP studies.
Keywords: Beamforming; Event-related potential (ERP); Independent component analysis (ICA); Pattern-reversal; Retinotopic mapping; Source localization; Visual cortex; Visual evoked potential (VEP).
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