Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.

This series of experiments investigated the neural basis of conscious vision in humans using a form of transcranial magnetic stimulation (TMS) known as continuous theta burst stimulation (cTBS). Previous studies have shown that occipital TMS, when time-locked to the onset of visual stimuli, can indu...

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Autores principales:	Christopher P G Allen, Benjamin T Dunkley, Suresh D Muthukumaraswamy, Richard Edden, C John Evans, Petroc Sumner, Krish D Singh, Christopher D Chambers
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2014
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/c0aa6204e4d34f01856651679227ea07
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spelling	oai:doaj.org-article:c0aa6204e4d34f01856651679227ea072021-11-18T08:14:39ZEnhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.1932-620310.1371/journal.pone.0100350https://doaj.org/article/c0aa6204e4d34f01856651679227ea072014-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24956195/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203This series of experiments investigated the neural basis of conscious vision in humans using a form of transcranial magnetic stimulation (TMS) known as continuous theta burst stimulation (cTBS). Previous studies have shown that occipital TMS, when time-locked to the onset of visual stimuli, can induce a phenomenon analogous to blindsight in which conscious detection is impaired while the ability to discriminate 'unseen' stimuli is preserved above chance. Here we sought to reproduce this phenomenon using offline occipital cTBS, which has been shown to induce an inhibitory cortical aftereffect lasting 45-60 minutes. Contrary to expectations, our first experiment revealed the opposite effect: cTBS enhanced conscious vision relative to a sham control. We then sought to replicate this cTBS-induced potentiation of consciousness in conjunction with magnetoencephalography (MEG) and undertook additional experiments to assess its relationship to visual cortical excitability and levels of the inhibitory neurotransmitter γ-aminobutyric acid (GABA; via magnetic resonance spectroscopy, MRS). Occipital cTBS decreased cortical excitability and increased regional GABA concentration. No significant effects of cTBS on MEG measures were observed, although the results provided weak evidence for potentiation of event related desynchronisation in the β band. Collectively these experiments suggest that, through the suppression of noise, cTBS can increase the signal-to-noise ratio of neural activity underlying conscious vision. We speculate that gating-by-inhibition in the visual cortex may provide a key foundation of consciousness.Christopher P G AllenBenjamin T DunkleySuresh D MuthukumaraswamyRichard EddenC John EvansPetroc SumnerKrish D SinghChristopher D ChambersPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 9, Iss 6, p e100350 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Christopher P G Allen Benjamin T Dunkley Suresh D Muthukumaraswamy Richard Edden C John Evans Petroc Sumner Krish D Singh Christopher D Chambers Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.
description	This series of experiments investigated the neural basis of conscious vision in humans using a form of transcranial magnetic stimulation (TMS) known as continuous theta burst stimulation (cTBS). Previous studies have shown that occipital TMS, when time-locked to the onset of visual stimuli, can induce a phenomenon analogous to blindsight in which conscious detection is impaired while the ability to discriminate 'unseen' stimuli is preserved above chance. Here we sought to reproduce this phenomenon using offline occipital cTBS, which has been shown to induce an inhibitory cortical aftereffect lasting 45-60 minutes. Contrary to expectations, our first experiment revealed the opposite effect: cTBS enhanced conscious vision relative to a sham control. We then sought to replicate this cTBS-induced potentiation of consciousness in conjunction with magnetoencephalography (MEG) and undertook additional experiments to assess its relationship to visual cortical excitability and levels of the inhibitory neurotransmitter γ-aminobutyric acid (GABA; via magnetic resonance spectroscopy, MRS). Occipital cTBS decreased cortical excitability and increased regional GABA concentration. No significant effects of cTBS on MEG measures were observed, although the results provided weak evidence for potentiation of event related desynchronisation in the β band. Collectively these experiments suggest that, through the suppression of noise, cTBS can increase the signal-to-noise ratio of neural activity underlying conscious vision. We speculate that gating-by-inhibition in the visual cortex may provide a key foundation of consciousness.
format	article
author	Christopher P G Allen Benjamin T Dunkley Suresh D Muthukumaraswamy Richard Edden C John Evans Petroc Sumner Krish D Singh Christopher D Chambers
author_facet	Christopher P G Allen Benjamin T Dunkley Suresh D Muthukumaraswamy Richard Edden C John Evans Petroc Sumner Krish D Singh Christopher D Chambers
author_sort	Christopher P G Allen
title	Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.
title_short	Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.
title_full	Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.
title_fullStr	Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.
title_full_unstemmed	Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.
title_sort	enhanced awareness followed reversible inhibition of human visual cortex: a combined tms, mrs and meg study.
publisher	Public Library of Science (PLoS)
publishDate	2014
url	https://doaj.org/article/c0aa6204e4d34f01856651679227ea07
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Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.

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