Article abstract


Nature Neuroscience 11, 1193 - 1200 (2008)
Published online: 24 August 2008 | doi:10.1038/nn.2173

Divergence of fMRI and neural signals in V1 during perceptual suppression in the awake monkey

Alexander Maier1, Melanie Wilke1, Christopher Aura1, Charles Zhu2, Frank Q Ye2 & David A Leopold1,2


The role of primary visual cortex (V1) in determining the contents of perception is controversial. Human functional magnetic resonance imaging (fMRI) studies of perceptual suppression have revealed a robust drop in V1 activity when a stimulus is subjectively invisible. In contrast, monkey single-unit recordings have failed to demonstrate such perception-locked changes in V1. To investigate the basis of this discrepancy, we measured both the blood oxygen level–dependent (BOLD) response and several electrophysiological signals in two behaving monkeys. We found that all signals were in good agreement during conventional stimulus presentation, showing strong visual modulation to presentation and removal of a stimulus. During perceptual suppression, however, only the BOLD response and the low-frequency local field potential (LFP) power showed decreases, whereas the spiking and high-frequency LFP power were unaffected. These results demonstrate that the coupling between the BOLD and electrophysiological signals in V1 is context dependent, with a marked dissociation occurring during perceptual suppression.

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  1. Unit on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, US National Institutes of Health, Department of Health and Human Services, 49 Convent Dr., B2J-45, MSC 4400, Bethesda, Maryland 20892, USA.
  2. Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, National Eye Institute, US National Institutes of Health, Department of Health and Human Services, 49 Convent Dr., B2J-45, MSC 4400, Bethesda, Maryland 20892, USA.

Correspondence to: Alexander Maier1 e-mail: maiera@mail.nih.gov



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