Eye movement-related confounds in neural decoding of visual working memory representations
Number of pages
SourceeNeuro, 5, 4, (2018), article ENEURO.0401-17.2018
Article / Letter to editor
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PI Group Predictive Brain
SW OZ DCC [ozi]
SW OZ DCC CO
SubjectAction, intention, and motor control; DI-BCB_DCC_Theme 2: Perception, Action and Control
A relatively new analysis technique, known as neural decoding or multivariate pattern analysis, has become increasingly popular for cognitive neuroimaging studies over recent years. These techniques promise to uncover the representational contents of neural signals, as well as the underlying code and the dynamic profile thereof. A field in which these techniques have led to novel insights in particular is that of visual working memory (VWM). In the present study we subjected human volunteers to a combined VWM/imagery task while recording their neural signals using MEG. We applied multivariate decoding analyses to uncover the temporal profile underlying the neural representations of the memorized item. Analysis of gaze position however revealed that our results were contaminated by systematic eye movements, suggesting that the MEG decoding results from our originally planned analyses were confounded. In addition to the eye movement analyses, we also present the original analyses to highlight how these might have readily led to invalid conclusions. Finally, we demonstrate a potential remedy, whereby we train the decoders on a functional localizer that was specifically designed to target bottom-up sensory signals and as such avoids eye movements. We conclude by arguing for more awareness of the potentially pervasive and ubiquitous effects of eye movement-related confounds.Significance Statement Neural decoding is an important and relatively novel technique that has opened up new avenues for cognitive neuroscience research. However, with its promises also come potential caveats. In this study we show that neural decoding may be susceptible to confounds induced by small task- and stimulus-specific eye movements in the context of a visual working memory task. Such eye movements during working memory tasks have been reported before, and may in fact be a common phenomenon. Given the widespread use of neural decoding and the potentially contaminating effects of eye movements, we therefore believe that our results are of significant relevance for the field.
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