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Causal manipulation of feed-forward and recurrent processing differentially affects measures of consciousness

Allen, Christopher, Viola, Tommaso, Irvine, Elizabeth ORCID:, Sedgmond, Jemma, Castle, Heidi, Gray, Richard ORCID: and Chambers, Christopher D. ORCID: 2020. Causal manipulation of feed-forward and recurrent processing differentially affects measures of consciousness. Neuroscience of Consciousness 2020 (1) , niaa015. 10.1093/nc/niaa015

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It has been theorized that cortical feed-forward and recurrent neural activity support unconscious and conscious cognitive processes, respectively. Here we causally tested this proposition by applying event-related transcranial magnetic stimulation (TMS) at early and late times relative to visual stimuli, together with a pulse designed to suppress conscious detection. Consistent with pre-registered hypotheses, early TMS affected residual, reportedly ‘unseen’ capacity. However, conscious perception also appeared critically dependent upon feed-forward processing to a greater extent than the later recurrent phase. Additional exploratory analyses suggested that these early effects dissociated from top-down criterion measures, which were most affected by later TMS. These findings are inconsistent with a simple dichotomy where feed-forward and recurrent processes correspond to unconscious and conscious mechanisms. Instead, different components of awareness may correspond to different phases of cortical dynamics in which initial processing is broadly perceptual whereas later recurrent processing might relate to decision to report.

Item Type: Article
Date Type: Publication
Status: Published
Schools: English, Communication and Philosophy
Cardiff University Brain Research Imaging Centre (CUBRIC)
Publisher: Oxford University Press
ISSN: 2057-2107
Funders: Wellcome Trust, BBSRC
Date of First Compliant Deposit: 19 May 2020
Date of Acceptance: 7 May 2020
Last Modified: 09 May 2023 03:32

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