Visual awareness suppression by pre-stimulus brain stimulation: a neural effect

C. Jacobs, R. Goebel, A.T. Sack

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Transcranial magnetic stimulation (TMS) has established the functional relevance of early visual cortex (EVC) for visual awareness with great temporal specificity non-invasively in conscious human volunteers. Many studies have found a suppressive effect when TMS was applied over EVC 80-100ms after the onset of the visual stimulus (post-stimulus TMS time window). Yet, few studies found task performance to also suffer when TMS was applied even before visual stimulus presentation (pre-stimulus TMS time window). This pre-stimulus TMS effect, however, remains controversially debated and its origin had mainly been ascribed to TMS-induced eye-blinking artifacts. Here, we applied chronometric TMS over EVC during the execution of a visual discrimination task, covering an exhaustive range of visual stimulus-locked TMS time windows ranging from -80 pre-stimulus to 300ms post-stimulus onset. Electrooculographical (EoG) recordings, sham TMS stimulation, and vertex TMS stimulation controlled for different types of non-neural TMS effects. Our findings clearly reveal TMS-induced masking effects for both pre- and post-stimulus time windows, and for both objective visual discrimination performance and subjective visibility. Importantly, all effects proved to be still present after post hoc removal of eye blink trials, suggesting a neural origin for the pre-stimulus TMS suppression effect on visual awareness. We speculate based on our data that TMS exerts its pre-stimulus effect via generation of a neural state which interacts with subsequent visual input. (PsycINFO Database Record (c) 2011 APA, all rights reserved) (journal abstract)
Original languageEnglish
Pages (from-to)616-624
Number of pages9
JournalNeuroimage
Volume59
Issue number1
DOIs
Publication statusPublished - 2 Jan 2012

Keywords

  • Consciousness
  • Early visual cortex
  • EoG
  • TMS
  • Visual discrimination
  • TRANSCRANIAL MAGNETIC STIMULATION
  • MOTION PERCEPTION
  • OCCIPITAL CORTEX
  • TEMPORAL CHARACTERISTICS
  • ADAPTATION PARADIGM
  • STATE-DEPENDENCY
  • V1/V2
  • AREAS
  • VISION

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