Extrageniculate Mediation of Unconscious Vision in Transcranial Magnetic Stimulation-Induced Blindsight

The proposed neural mechanisms supporting blindsight, the above-chance performance of cortically blind patients on forced-choice visual discrimination tasks, are controversial. In this article, we show that although subjects were unable to perceive foveally presented visual stimuli when transcranial...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 101; no. 26; pp. 9933 - 9935
Main Authors Ro, Tony, Shelton, Dominique, Lee, Olivia L., Chang, Erik, Treisman, Anne
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences 29.06.2004
National Acad Sciences
Subjects
Adult
Analysis of Variance
Biological Sciences
Blindness - complications
Blindness - physiopathology
Experimentation
Eyes & eyesight
Female
Fovea Centralis - physiology
Humans
Male
Perceptions
Perceptual localization
Photic Stimulation
Psychology
Saccades
Saccades - physiology
Scotoma
Scotoma - complications
Scotoma - physiopathology
Superior Colliculi - physiology
Superior colliculus
T tests
Time Factors
Transcranial Magnetic Stimulation
Unconscious mind
Unconsciousness
Vision, Ocular - physiology
Visual cortex
Visual Perception - physiology
Visual stimulation
Online AccessGet full text
ISSN0027-8424
1091-6490
DOI10.1073/pnas.0403061101

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Summary:The proposed neural mechanisms supporting blindsight, the above-chance performance of cortically blind patients on forced-choice visual discrimination tasks, are controversial. In this article, we show that although subjects were unable to perceive foveally presented visual stimuli when transcranial magnetic stimulation over the visual cortex induced a scotoma, responses nonetheless were delayed significantly by these unconscious distractors in a directed saccade but not in an indirect manual response task. These results suggest that the superior colliculus, which is involved with sensory encoding as well as with the generation of saccadic eye movements, is mediating the unconscious processing of the transcranial magnetic stimulation-suppressed distractors and implicate a role of the retinotectal pathway in many blindsight phenomena.
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Edited by Anne Treisman, Princeton University, Princeton, NJ, and approved May 18, 2004
Abbreviations: TMS, transcranial magnetic stimulation; RT, reaction time.
This paper was submitted directly (Track II) to the PNAS office.
To whom correspondence should be addressed. E-mail: tro@rice.edu.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0403061101