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The Journal of Neuroscience, December 31, 2008, 28(53):14481-14485; doi:10.1523/JNEUROSCI.4398-08.2008

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Brief Communications
Ongoing Activity Fluctuations in hMT+ Bias the Perception of Coherent Visual Motion

Guido Hesselmann,^1,2,3 Christian A. Kell,⁴ and Andreas Kleinschmidt^1,2,3

¹INSERM, Unité 562, Cognitive Neuroimaging, ²Commissariat à l'Energie Atomique, Direction des Sciences du Vivant, Institut d'Imagerie Biomédicale, NeuroSpin, 91191 Gif-sur-Yvette, France, ³Université Paris-Sud, 91405 Orsay, France, and ⁴Department of Neurology, Johann Wolfgang Goethe University, D-60325 Frankfurt am Main, Germany

Correspondence should be addressed to Guido Hesselmann, INSERM Unité 562, NeuroSpin/Commissariat à l'Energie Atomique, 91191 Gif-sur-Yvette, France. Email: g.hesselmann{at}gmail.com

We have recently shown that intrinsic fluctuations of ongoing activity during baseline have an impact on perceptual decisions reported for an ambiguous visual stimulus (Hesselmann et al., 2008). To test whether this result generalizes from the visual object domain to other perceptual and neural systems, the current study investigated the effect of ongoing signal fluctuations in motion-sensitive brain regions on the perception of coherent visual motion. We determined motion coherence thresholds individually for each subject using a dynamic random dot display. During functional magnetic resonance imaging (fMRI), brief events of subliminal, supraliminal, and periliminal coherent motion were presented with long and variable interstimulus intervals between them. On each trial, subjects reported whether they had perceived "coherent" or "random" motion, and fMRI signal time courses were analyzed separately as a function of stimulus and percept type. In the right motion-sensitive occipito-temporal cortex (hMT+), coherent percepts of periliminal stimuli yielded a larger stimulus-evoked response than random percepts. Prestimulus baseline activity in this region was also significantly higher in these coherent trials than in random trials. As in our previous study, however, the relation between ongoing and evoked activity was not additive but interacted with perceptual outcome. Our data thus suggest that endogenous fluctuations in baseline activity have a generic effect on subsequent perceptual decisions. Although mainstream analytical techniques used in functional neuroimaging do not capture this nonadditive effect of baseline on evoked response, it is in accord with postulates from theoretical frameworks as, for instance, predictive coding.

Key words: predictive coding; perceptual decision; visual awareness; BOLD fMRI; prestimulus activity; consciousness

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Received Sept. 15, 2008; revised Nov. 6, 2008; accepted Nov. 22, 2008.

Correspondence should be addressed to Guido Hesselmann, INSERM Unité 562, NeuroSpin/Commissariat à l'Energie Atomique, 91191 Gif-sur-Yvette, France. Email: g.hesselmann{at}gmail.com

This article has been cited by other articles:

				V. Wyart and C. Tallon-Baudry How Ongoing Fluctuations in Human Visual Cortex Predict Perceptual Awareness: Baseline Shift versus Decision Bias J. Neurosci., July 8, 2009; 29(27): 8715 - 8725. [Abstract] [Full Text] [PDF]

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