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Cereb Cortex. 2016 Jul;26(7):3146-60. doi: 10.1093/cercor/bhv146. Epub 2015 Jul 4.

Expecting to See a Letter: Alpha Oscillations as Carriers of Top-Down Sensory Predictions.

Author information

1
Department of Neurophysiology, Max Planck Institute for Brain Research, Frankfurt am Main, Germany.
2
The Rockefeller University, New York, NY, USA.
3
MEG Unit, Brain Imaging Center, Goethe University, Frankfurt am Main, Germany.
4
Department of Neurophysiology, Max Planck Institute for Brain Research, Frankfurt am Main, Germany Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany Ernst Strüngmann Institute for Neuroscience in Cooperation with Max Planck Society, Frankfurt am Main, Germany.
5
Department of Neurophysiology, Max Planck Institute for Brain Research, Frankfurt am Main, Germany Columbia University Medical Center, New York, NY, USA NYU Langone Medical Center, New York, NY, USA.

Abstract

Predictions strongly influence perception. However, the neurophysiological processes that implement predictions remain underexplored. It has been proposed that high- and low-frequency neuronal oscillations act as carriers of sensory evidence and top-down predictions, respectively (von Stein and Sarnthein 2000; Bastos et al. 2012). However, evidence for the latter hypothesis remains scarce. In particular, it remains to be shown whether slow prestimulus alpha oscillations in task-relevant brain regions are stronger in the presence of predictions, whether they influence early categorization processes, and whether this interplay indeed boosts perception. Here, we directly address these questions by manipulating subjects' prior expectations about the identity of visually presented letters while collecting magnetoencephalographic recordings. We find that predictions lead to increased prestimulus alpha oscillations in a multisensory network representing grapheme/phoneme associations. Furthermore, alpha power interacts with stimulus degradation and top-down expectations to predict visibility ratings, and correlates with the amplitude of early sensory components (P1/N1m complex), suggesting a role in the selective amplification of predicted information. Our results thus indicate that low-frequency alpha oscillations can serve as a mechanism to carry and test sensory predictions about letters.

KEYWORDS:

alpha oscillations; sensory predictions; top-down

PMID:
26142463
DOI:
10.1093/cercor/bhv146
[Indexed for MEDLINE]

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