Temporal Expectation Improves Real-Time Decoding of Visual Feature Representations as Measured By Magnetoencephalography
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1
University of Oxford, Experimental Psychology, United Kingdom
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2
University of Oxford, Oxford Centre for Human Brain Activity, United Kingdom
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3
Ecole Normale Supérieure, Département d'Etudes Cognitives, France
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4
University of Oxford, Oxford Centre for Human Brain Activity, United Kingdom
Temporal expectation is increasingly understood to improve the perceptual analysis of visual stimuli. Rhythms are arguably the most common source of temporal predictions of events. Recent evidence has shown that entrainment of sensory areas to rhythmic stimulus presentation improves perceptual gain of attended stimuli. However, it is unknown how this modulation occurs. One possibility is that temporal expectation improves perception by sharpening the neural representation of visual stimuli. Here, we tested this idea using magnetoencephalography (MEG) in combination with electroencephalography (EEG) and multivariate pattern analysis to see whether decoding accuracy improves when stimuli are presented rhythmically.
We measured brain activity via combined MEG-EEG in 10 observers as they performed a visual target detection task. In regular rhythmic blocks, observers saw streams of oriented gratings appearing rhythmically at 1.54 Hz, and responded with a button press every time they saw the target orientation. In irregular rhythmic blocks, stimuli were also presented at an average rate of 1.54 Hz, but individual stimulus onsets were temporally jittered around this average, reducing their temporal predictability. Target orientations could change from block to block.
The orientation of each presented grating was decoded from the MEG and EEG data using a multivariate pattern analysis approach that capitalizes on the parametric nature of the orientation feature space via a forward encoding model. Orientations could be decoded robustly in a range between approximately 100 and 400 ms after stimulus onset (p<10-5 in regular and irregular blocks). We found that stimulus decoding was significantly higher in regular blocks, compared to irregular blocks, beginning around 200 ms (175-225 ms, p=0.035), and lasting between approximately 200 and 400 ms (p=0.019). We conclude that rhythmic temporal expectation sharpens the neural representation of task-relevant visual features.
Keywords:
Attention,
Magnetoencephalography,
multivariate pattern analysis,
entrainment,
visual discrimination,
temporal attention
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Oral Presentation
Topic:
Attention
Citation:
Myers
N,
Rohenkohl
G,
Wyart
V,
Stokes
MG and
Nobre
AC
(2015). Temporal Expectation Improves Real-Time Decoding of Visual Feature Representations as Measured By Magnetoencephalography.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00085
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Mr. Nicholas Myers, University of Oxford, Experimental Psychology, Oxford, United Kingdom, nicholas.myers@psy.ox.ac.uk