The current work examined neural substrates of perceptual grouping in human visual cortex using event-related potential (ERP) recording. Stimulus arrays consisted of local elements that were either evenly spaced (unif...The current work examined neural substrates of perceptual grouping in human visual cortex using event-related potential (ERP) recording. Stimulus arrays consisted of local elements that were either evenly spaced (uniform stimuli) or grouped into columns or rows by prox-imity or color similarity (grouping stimuli). High-density ERPs were recorded while subjects identified orientations of perceptual groups in stimulus arrays that were presented randomly in one of the four quadrants of the visual field. Both uniform and grouping stimulus arrays elicited an early ERP component (C1), which peaked at about 70 ms after stimulus onset and changed its polarity as a function of stimulated elevations. Dipole modeling based on realistic- head boundary-element models revealed generators of the C1 component in the calcarine cortex. The C1 was modu-lated by perceptual grouping of local elements based on proximity, and this grouping effect was stronger in the upper than in the lower visual field. The findings provide ERP evi-dence for the engagement of human primary visual cortex in the early stage of perceptual grouping.展开更多
A study-test paradigm was used to investigate the Dm (Differential memory) effect and the old/new effect of pictures. The participants were asked to judge whether the pictures were previously studied or not when they ...A study-test paradigm was used to investigate the Dm (Differential memory) effect and the old/new effect of pictures. The participants were asked to judge whether the pictures were previously studied or not when they were pre-sented with a series of pictures during the test phase. The event-related potentials (ERPs) were recorded during en-coding and retrieval phases. The results showed that (1) during 400—700 ms of encoding, the remembered old pic-tures elicited more positive waveforms than the forgotten old pictures at frontal and central areas; (2) during 500—600 ms of retrieval, the correctly judged old pictures elicited more positive waveforms than the correctly judged new pictures at medial-midline in both hemispheres; (3) the duration of Dm effect was longer than that of old/new effect for picture. The present results suggest that the Dm effect of pictures is dif-ferent from that of words and faces in spatial and temporal distributions. The neural mechanisms of picture encoding and picture retrieval are also different, which indicates that retrieval is not the simple recovery of encoding.展开更多
文摘The current work examined neural substrates of perceptual grouping in human visual cortex using event-related potential (ERP) recording. Stimulus arrays consisted of local elements that were either evenly spaced (uniform stimuli) or grouped into columns or rows by prox-imity or color similarity (grouping stimuli). High-density ERPs were recorded while subjects identified orientations of perceptual groups in stimulus arrays that were presented randomly in one of the four quadrants of the visual field. Both uniform and grouping stimulus arrays elicited an early ERP component (C1), which peaked at about 70 ms after stimulus onset and changed its polarity as a function of stimulated elevations. Dipole modeling based on realistic- head boundary-element models revealed generators of the C1 component in the calcarine cortex. The C1 was modu-lated by perceptual grouping of local elements based on proximity, and this grouping effect was stronger in the upper than in the lower visual field. The findings provide ERP evi-dence for the engagement of human primary visual cortex in the early stage of perceptual grouping.
文摘A study-test paradigm was used to investigate the Dm (Differential memory) effect and the old/new effect of pictures. The participants were asked to judge whether the pictures were previously studied or not when they were pre-sented with a series of pictures during the test phase. The event-related potentials (ERPs) were recorded during en-coding and retrieval phases. The results showed that (1) during 400—700 ms of encoding, the remembered old pic-tures elicited more positive waveforms than the forgotten old pictures at frontal and central areas; (2) during 500—600 ms of retrieval, the correctly judged old pictures elicited more positive waveforms than the correctly judged new pictures at medial-midline in both hemispheres; (3) the duration of Dm effect was longer than that of old/new effect for picture. The present results suggest that the Dm effect of pictures is dif-ferent from that of words and faces in spatial and temporal distributions. The neural mechanisms of picture encoding and picture retrieval are also different, which indicates that retrieval is not the simple recovery of encoding.
