The effect of spatial resolution on decoding accuracy in fMRI multivariate pattern analysis

Gardumi, Anna; Ivanov, Dimo; Hausfeld, Lars; Valente, Giancarlo; Formisano, Elia; Uludağ, Kâmil

doi:10.1016/j.neuroimage.2016.02.033

Cited by 105 publications

(94 citation statements)

References 36 publications

(67 reference statements)

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“…Successful classification of ILD values was observed across a range of conditions, with performance exceeding chance levels by up to 22%. That performance is roughly on par with other attempts at multi-voxel classification in the auditory system (De Martino et al, 2008; Obleser et al, 2010; Kumar et al, 2014; Gardumi et al, 2016). …”

Section: Resultssupporting

confidence: 68%

Sensitivity to an Illusion of Sound Location in Human Auditory Cortex

Higgins¹,

McLaughlin²,

Costa³

et al. 2017

Front. Syst. Neurosci.

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Human listeners place greater weight on the beginning of a sound compared to the middle or end when determining sound location, creating an auditory illusion known as the Franssen effect. Here, we exploited that effect to test whether human auditory cortex (AC) represents the physical vs. perceived spatial features of a sound. We used functional magnetic resonance imaging (fMRI) to measure AC responses to sounds that varied in perceived location due to interaural level differences (ILD) applied to sound onsets or to the full sound duration. Analysis of hemodynamic responses in AC revealed sensitivity to ILD in both full-cue (veridical) and onset-only (illusory) lateralized stimuli. Classification analysis revealed regional differences in the sensitivity to onset-only ILDs, where better classification was observed in posterior compared to primary AC. That is, restricting the ILD to sound onset—which alters the physical but not the perceptual nature of the spatial cue—did not eliminate cortical sensitivity to that cue. These results suggest that perceptual representations of auditory space emerge or are refined in higher-order AC regions, supporting the stable perception of auditory space in noisy or reverberant environments and forming the basis of illusions such as the Franssen effect.

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Section: Resultssupporting

confidence: 68%

Sensitivity to an Illusion of Sound Location in Human Auditory Cortex

Higgins¹,

McLaughlin²,

Costa³

et al. 2017

Front. Syst. Neurosci.

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“…The warping parameters were then separately applied to the functional and structural images to produce normalized images of resolution 2 × 2 × 2 mm 3 and 1 × 1 × 1 mm 3 , respectively. Finally the warped functional images were spatially smoothed with a Gaussian kernel of 4 mm FWHM to improve signal-to-noise ratio while preserving the underlying spatial distribution (Schrouff, Kussé, Wehenkel, Maquet, & Phillips, 2012); this smoothing also diminishes the impact residual head motion can have on MVPA performance, even after head motion correction (Gardumi et al, 2012).…”

Section: Image Preprocessingmentioning

confidence: 99%

The Dorsal Attention Network Reflects Both Encoding Load and Top–down Control during Working Memory

Majerus

Peters

Bouffier

et al. 2018

Journal of Cognitive Neuroscience

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Abstract■ The dorsal attention network is consistently involved in verbal and visual working memory ( WM) tasks and has been associated with task-related, top-down control of attention. At the same time, WM capacity has been shown to depend on the amount of information that can be encoded in the focus of attention independently of top-down strategic control. We examined the role of the dorsal attention network in encoding load and top-down memory control during WM by manipulating encoding load and memory control requirements during a short-term probe recognition task for sequences of auditory (digits, letters) or visual (lines, unfamiliar faces) stimuli. Encoding load was manipulated by presenting sequences with small or large sets of memoranda while maintaining the amount of sensory stimuli constant. Top-down control was manipulated by instructing participants to passively maintain all stimuli or to selectively maintain stimuli from a predefined category. By using ROI and searchlight multivariate analysis strategies, we observed that the dorsal attention network encoded information for both load and control conditions in verbal and visuospatial modalities. Decoding of load conditions was in addition observed in modality-specific sensory cortices. These results highlight the complexity of the role of the dorsal attention network in WM by showing that this network supports both quantitative and qualitative aspects of attention during WM encoding, and this is in a partially modality-specific manner. ■

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“…Hence, we emphasize the importance of thinking about this choice. As an interesting example, Gardumi et al (32) studied the effect of smoothing on their dataset and decided to use the optimal smoothing level only after careful examination.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Spatial Smoothing on Representational Similarity in a Simple Motor Paradigm

et al. 2017

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Multi-voxel pattern analyses (MVPA) are often performed on unsmoothed data, which is very different from the general practice of large smoothing extents in standard voxel-based analyses. In this report, we studied the effect of smoothing on MVPA results in a motor paradigm. Subjects pressed four buttons with two different fingers of the two hands in response to auditory commands. Overall, independent of the degree of smoothing, correlational MVPA showed distinctive patterns for the different hands in all studied regions of interest (motor cortex, prefrontal cortex, and auditory cortices). With regard to the effect of smoothing, our findings suggest that results from correlational MVPA show a minor sensitivity to smoothing. Moderate amounts of smoothing (in this case, 1−4 times the voxel size) improved MVPA correlations, from a slight improvement to large improvements depending on the region involved. None of the regions showed signs of a detrimental effect of moderate levels of smoothing. Even higher amounts of smoothing sometimes had a positive effect, most clearly in low-level auditory cortex. We conclude that smoothing seems to have a minor positive effect on MVPA results, thus researchers should be mindful about the choices they make regarding the level of smoothing.

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The effect of spatial resolution on decoding accuracy in fMRI multivariate pattern analysis

Cited by 105 publications

References 36 publications

Sensitivity to an Illusion of Sound Location in Human Auditory Cortex

Sensitivity to an Illusion of Sound Location in Human Auditory Cortex

The Dorsal Attention Network Reflects Both Encoding Load and Top–down Control during Working Memory

The Effect of Spatial Smoothing on Representational Similarity in a Simple Motor Paradigm

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