Neuronavigated TMS of early visual cortex eliminates unconscious processing of chromatic stimuli

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Neuronavigated TMS of early visual cortex eliminates unconscious processing of chromatic stimuli. / Hurme, Mikko; Koivisto, Mika; Henriksson, Linda; Railo, Henry.

julkaisussa: Neuropsychologia, Vuosikerta 136, 107266, 01.01.2020.

Tutkimustuotos: Lehtiartikkelivertaisarvioitu

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@article{4826df8fff32414791342dd764b09b7a,
title = "Neuronavigated TMS of early visual cortex eliminates unconscious processing of chromatic stimuli",
abstract = "Some neurological patients with primary visual cortex (V1) lesions can guide their behavior based on stimuli presented to their blind visual field. One example of this phenomenon is the ability to discriminate colors in the absence of awareness. These so-called patients with blindsight must have a neural pathway that bypasses V1, explaining their ability to unconsciously process stimuli. The pathways that have been most often hypothesized to be the cause of blindsight connect lateral geniculate nucleus (LGN) or superior colliculus (SC) to extrastriate cortex, most likely V5, and parietal areas. To test if similar pathways function in neurologically healthy individuals or if unconscious processing depends on early visual cortex, we disturbed the visibility of a chromatic stimulus with metacontrast masking (Experiment 1) or neuronavigated transcranial magnetic stimulation (TMS) of early visual cortex, exact target being retinotopically mapped V1 (Experiment 2). We measured unconscious processing using the redundant target effect (RTE), which is the speeding up of reaction times in response to dual stimuli compared with one stimulus, when the task is to respond to any number of stimuli. An unconscious chromatic RTE was found when the visibility of the redundant chromatic stimulus was suppressed with a visual mask. When TMS was targeted to the correct retinotopic location of V1, and conscious perception of the redundant chromatic stimulus suppressed, the RTE was eliminated. Whether the elimination of unconscious RTE during TMS was exclusively due to disruption of V1 activity, or whether it was due to the possible interference with processing in V2 or even V3, is discussed. Based on our results and converging evidence from previous studies, we conclude that unconscious processing of chromatic information depends on the early visual cortex, in neurologically healthy participants.",
keywords = "Blindsight, Color perception, Early visual cortex, Redundant target effect, TMS, Unconscious vision, V1",
author = "Mikko Hurme and Mika Koivisto and Linda Henriksson and Henry Railo",
year = "2020",
month = "1",
day = "1",
doi = "10.1016/j.neuropsychologia.2019.107266",
language = "English",
volume = "136",
journal = "Neuropsychologia",
issn = "0028-3932",

}

RIS - Lataa

TY - JOUR

T1 - Neuronavigated TMS of early visual cortex eliminates unconscious processing of chromatic stimuli

AU - Hurme, Mikko

AU - Koivisto, Mika

AU - Henriksson, Linda

AU - Railo, Henry

PY - 2020/1/1

Y1 - 2020/1/1

N2 - Some neurological patients with primary visual cortex (V1) lesions can guide their behavior based on stimuli presented to their blind visual field. One example of this phenomenon is the ability to discriminate colors in the absence of awareness. These so-called patients with blindsight must have a neural pathway that bypasses V1, explaining their ability to unconsciously process stimuli. The pathways that have been most often hypothesized to be the cause of blindsight connect lateral geniculate nucleus (LGN) or superior colliculus (SC) to extrastriate cortex, most likely V5, and parietal areas. To test if similar pathways function in neurologically healthy individuals or if unconscious processing depends on early visual cortex, we disturbed the visibility of a chromatic stimulus with metacontrast masking (Experiment 1) or neuronavigated transcranial magnetic stimulation (TMS) of early visual cortex, exact target being retinotopically mapped V1 (Experiment 2). We measured unconscious processing using the redundant target effect (RTE), which is the speeding up of reaction times in response to dual stimuli compared with one stimulus, when the task is to respond to any number of stimuli. An unconscious chromatic RTE was found when the visibility of the redundant chromatic stimulus was suppressed with a visual mask. When TMS was targeted to the correct retinotopic location of V1, and conscious perception of the redundant chromatic stimulus suppressed, the RTE was eliminated. Whether the elimination of unconscious RTE during TMS was exclusively due to disruption of V1 activity, or whether it was due to the possible interference with processing in V2 or even V3, is discussed. Based on our results and converging evidence from previous studies, we conclude that unconscious processing of chromatic information depends on the early visual cortex, in neurologically healthy participants.

AB - Some neurological patients with primary visual cortex (V1) lesions can guide their behavior based on stimuli presented to their blind visual field. One example of this phenomenon is the ability to discriminate colors in the absence of awareness. These so-called patients with blindsight must have a neural pathway that bypasses V1, explaining their ability to unconsciously process stimuli. The pathways that have been most often hypothesized to be the cause of blindsight connect lateral geniculate nucleus (LGN) or superior colliculus (SC) to extrastriate cortex, most likely V5, and parietal areas. To test if similar pathways function in neurologically healthy individuals or if unconscious processing depends on early visual cortex, we disturbed the visibility of a chromatic stimulus with metacontrast masking (Experiment 1) or neuronavigated transcranial magnetic stimulation (TMS) of early visual cortex, exact target being retinotopically mapped V1 (Experiment 2). We measured unconscious processing using the redundant target effect (RTE), which is the speeding up of reaction times in response to dual stimuli compared with one stimulus, when the task is to respond to any number of stimuli. An unconscious chromatic RTE was found when the visibility of the redundant chromatic stimulus was suppressed with a visual mask. When TMS was targeted to the correct retinotopic location of V1, and conscious perception of the redundant chromatic stimulus suppressed, the RTE was eliminated. Whether the elimination of unconscious RTE during TMS was exclusively due to disruption of V1 activity, or whether it was due to the possible interference with processing in V2 or even V3, is discussed. Based on our results and converging evidence from previous studies, we conclude that unconscious processing of chromatic information depends on the early visual cortex, in neurologically healthy participants.

KW - Blindsight

KW - Color perception

KW - Early visual cortex

KW - Redundant target effect

KW - TMS

KW - Unconscious vision

KW - V1

UR - http://www.scopus.com/inward/record.url?scp=85075443958&partnerID=8YFLogxK

U2 - 10.1016/j.neuropsychologia.2019.107266

DO - 10.1016/j.neuropsychologia.2019.107266

M3 - Article

C2 - 31758972

AN - SCOPUS:85075443958

VL - 136

JO - Neuropsychologia

JF - Neuropsychologia

SN - 0028-3932

M1 - 107266

ER -

ID: 39308845