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Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans

Orientation contrast is formed when some elements orient differently from their surroundings. Although orientation contrast can be processed in the absence of top-down attention, the underlying neural mechanism for this automatic processing in humans is controversial. In particular, whether automati...

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Autores principales: Zhen, Yanfen, Li, Duo, Ding, Ran, Huang, Zili, Qu, Zhe, Ding, Yulong
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6174204/
https://www.ncbi.nlm.nih.gov/pubmed/30327594
http://dx.doi.org/10.3389/fnhum.2018.00369
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author Zhen, Yanfen
Li, Duo
Ding, Ran
Huang, Zili
Qu, Zhe
Ding, Yulong
author_facet Zhen, Yanfen
Li, Duo
Ding, Ran
Huang, Zili
Qu, Zhe
Ding, Yulong
author_sort Zhen, Yanfen
collection PubMed
description Orientation contrast is formed when some elements orient differently from their surroundings. Although orientation contrast can be processed in the absence of top-down attention, the underlying neural mechanism for this automatic processing in humans is controversial. In particular, whether automatic detection of orientation contrast occurs at the initial feedforward stage in the primary visual cortex (i.e., V1) remains unclear. Here, we used event-related potentials (ERPs) to examine the automatic processing of orientation contrast in humans. In three experiments, participants completed a task at fixation while orientation contrasts were presented in the periphery, either in the upper visual field (UVF) or the lower visual field (LVF). All experiments showed significant positive potentials evoked by orientation contrasts over occipital areas within 100 ms after stimulus onset. These contrast effects occurred 10–20 ms later than the C1 components evoked by identically located abrupt onset stimuli which indexes the initial feedforward activity in V1. Compared with those in the UVF, orientation contrasts in the LVF evoked earlier and stronger activities, probably reflecting a LVF advantage in processing of orientation contrast. Even when orientation contrasts were rendered almost invisible by backward masking (in Experiment 2), the early contrast effect in the LVF was not disrupted. These findings imply that automatic processing of orientation contrast could occur at early visual cortical processing stages, but was slightly later than the initial feedforward processing in human V1; such automatic processing may involve either recurrent processing in V1 or feedforward processing in early extrastriate visual cortex. Highlights: -. We examined the earliest automatic processing of orientation contrast in humans with ERPs. -. Significant orientation contrast effect started within 100 ms in early visual areas. -. The earliest orientation contrast effect occurred later than the C1 evoked by abrupt onset stimuli. -. The earliest orientation contrast effect was independent of top-down attention and awareness. -. Automatic detection of orientation contrast arises slightly after the initial feedforward processing in V1.
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spelling pubmed-61742042018-10-16 Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans Zhen, Yanfen Li, Duo Ding, Ran Huang, Zili Qu, Zhe Ding, Yulong Front Hum Neurosci Neuroscience Orientation contrast is formed when some elements orient differently from their surroundings. Although orientation contrast can be processed in the absence of top-down attention, the underlying neural mechanism for this automatic processing in humans is controversial. In particular, whether automatic detection of orientation contrast occurs at the initial feedforward stage in the primary visual cortex (i.e., V1) remains unclear. Here, we used event-related potentials (ERPs) to examine the automatic processing of orientation contrast in humans. In three experiments, participants completed a task at fixation while orientation contrasts were presented in the periphery, either in the upper visual field (UVF) or the lower visual field (LVF). All experiments showed significant positive potentials evoked by orientation contrasts over occipital areas within 100 ms after stimulus onset. These contrast effects occurred 10–20 ms later than the C1 components evoked by identically located abrupt onset stimuli which indexes the initial feedforward activity in V1. Compared with those in the UVF, orientation contrasts in the LVF evoked earlier and stronger activities, probably reflecting a LVF advantage in processing of orientation contrast. Even when orientation contrasts were rendered almost invisible by backward masking (in Experiment 2), the early contrast effect in the LVF was not disrupted. These findings imply that automatic processing of orientation contrast could occur at early visual cortical processing stages, but was slightly later than the initial feedforward processing in human V1; such automatic processing may involve either recurrent processing in V1 or feedforward processing in early extrastriate visual cortex. Highlights: -. We examined the earliest automatic processing of orientation contrast in humans with ERPs. -. Significant orientation contrast effect started within 100 ms in early visual areas. -. The earliest orientation contrast effect occurred later than the C1 evoked by abrupt onset stimuli. -. The earliest orientation contrast effect was independent of top-down attention and awareness. -. Automatic detection of orientation contrast arises slightly after the initial feedforward processing in V1. Frontiers Media S.A. 2018-10-01 /pmc/articles/PMC6174204/ /pubmed/30327594 http://dx.doi.org/10.3389/fnhum.2018.00369 Text en Copyright © 2018 Zhen, Li, Ding, Huang, Qu and Ding. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Neuroscience
Zhen, Yanfen
Li, Duo
Ding, Ran
Huang, Zili
Qu, Zhe
Ding, Yulong
Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans
title Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans
title_full Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans
title_fullStr Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans
title_full_unstemmed Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans
title_short Automatic Detection of Orientation Contrast Occurs at Early but Not Earliest Stages of Visual Cortical Processing in Humans
title_sort automatic detection of orientation contrast occurs at early but not earliest stages of visual cortical processing in humans
topic Neuroscience
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6174204/
https://www.ncbi.nlm.nih.gov/pubmed/30327594
http://dx.doi.org/10.3389/fnhum.2018.00369
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