The effects of single-trial averaging upon the spatial extent of fMRI activation

Huettel, Scott A.; McCarthy, Gregory

doi:10.1097/00001756-200108080-00025

Cited by 87 publications

(52 citation statements)

References 13 publications

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“…the spatial extent of activation increased monotonically and failed to asymptote even after 22 scans (Saad et al, 2003). Huettel and McCarthy have reported a similar result in an event-related task (Huettel and McCarthy, 2001). It was found that at a number of events typical of fMRI experiments (i.e., 50 trials), only 50% of the eventually active voxels were found to show a significant effect.…”

Section: Introductionmentioning

confidence: 64%

“…These activation maps were then thresholded and the number of active voxels in the ROIs derived above was counted. The correlation analysis maps were thresholded at P < 0.001 (t > 3.88341) as in Huettel and McCarthy (2001). The GLM analysis activation maps were also thresholded at P < 0.001 (z = 3.1).…”

Section: Permutation Analysesmentioning

confidence: 99%

“…However, the number of events required to produce stable activation maps is a poorly investigated and understood problem. Huettel and McCarthy [Huettel, S.A., McCarthy, G., 2001. The effects of single-trial averaging upon the spatial extent of fMRI activation.…”

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confidence: 99%

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Neural mechanisms involved in error processing: A comparison of errors made with and without awareness

et al. 2005

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Event-related fMRI is a powerful tool for localising psychological functions to specific brain areas. However, the number of events required to produce stable activation maps is a poorly investigated and understood problem. Huettel and McCarthy [Huettel, S.A., McCarthy, G., 2001. The effects of single-trial averaging upon the spatial extent of fMRI activation. NeuroReport 12, 2411 -2416] have shown that the spatial extent of activation increases monotonically with the number of events in an analysis. In the present paper, this result is replicated and shown to be a consequence of the cross-correlation technique used to determine active voxels and does not hold, for example, for a GLM analysis. Another analysis technique, that does not depend on goodness-of-fit to the data, is also proposed. This technique calculates an impulse response function (IRF) for each voxel, finds the best fitting haemodynamic shape to the IRF and returns an area-under-the-curve (%AUC) activation measure. Using spatial extent as a measure, asymptotic behaviour is evident after as few as 25 events for the %AUC analysis technique in a finger-tapping task with non-overlapping haemodynamic responses and for both the GLM and %AUC techniques in a similar task that allows responses to overlap. The experimental validity of the %AUC technique to identify active brain regions while minimising false positive levels is demonstrated in a group study with 25 participants. D

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Section: Introductionmentioning

confidence: 64%

Section: Permutation Analysesmentioning

confidence: 99%

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Neural mechanisms involved in error processing: A comparison of errors made with and without awareness

et al. 2005

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“…These studies included twenty subjects each and were conducted to find an appropriate experimental design for the present fMRI study. Huettel and McCarthy, 2001). Furthermore, a third pilot study was conducted to test whether background colors will get associated with the emotional valence of the facial expression with which they were combined during the first experimental run.…”

Section: Pilot Studiesmentioning

confidence: 99%

Interference control during recognition of facial affect enhances the processing of expression specific properties — An event-related fMRI study

2009

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Though we can almost pre-attentively categorize the valence of facial expressions, we experience emotional ambiguity when confronted with facial expressions in a context with incongruent emotional information. We simultaneously presented interfering background colors during forced-choice categorizations of negative (fear), neutral and positive (happy) expressions. Conflicting information induced strong and differential interference effects on a behavioral level which was mirrored in comparable activations on a neuronal level.Besides a common fronto-parietal attention network which was activated during interference resolution, we found differential interference effects for facial expressions. IntroductionFrom an ecological perspective, facial expressions always appear in a broader temporal and spatial context. Contextual features are often relevant for a unique interpretation of facial expressions, but emotional incongruent contextual features might also introduce ambiguity during recognition of facial expressions.Several studies by de Gelder and her colleagues (Meeren et al., 2005;Righart and de Gelder, 2006) demonstrated that different components of event-related potentials during emotional face processing are modulated by contextual stimulus features. These authors, for instance, demonstrated a modulation of the visual P1 component by emotional incongruent compounds of facial expressions and emotional body postures (Meeren et al., 2005). Additionally, a modulation of the face-

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“…The standard deviation of the noise was varied between 3.2 and 4 leading to signal-to-noise ratios (SNR, ratio of the mean of the MR signal to the standard deviation of the noise [Huettel and McCarthy, 2001b]) of approximately 210, 190, and 170 in three different variations of each simulated time-series. All resulting simulated time-series data were analyzed using general linear model with FIR predictors, identical to analysis of the empirical data.…”

Section: Simulated Experimentsmentioning

confidence: 99%

Stimulus repetition and hemodynamic response refractoriness in event‐related fMRI

Soon

Venkatraman

Chee

2003

Human Brain Mapping

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Abstract:We investigated the extent of hemodynamic recovery following the paired presentation of either identical or different faces at two different inter-stimulus intervals (ISI). Signal recovery was consistently better at an ISI of 6 sec compared to 3 sec. Significantly less signal recovery was associated with identical faces compared to different faces in bilateral mid-fusiform and right prefrontal regions but not in the calcarine and posterior fusiform regions. Repetition suppression effects contributed significantly to incomplete signal recovery in a region-specific manner. Simulations using empirically derived data suggest that experiments with shorter ISI (average 4.5-6.0 sec) are as sensitive as experiments with intermediate ISI (average 9 sec) in detecting response differences if experimental duration is equivalent. However, designs using intermediate ISI may be more appropriate if the expected difference in responses is small and if the number of suitable stimuli is limited. Hum. Brain Mapping 20:1-12, 2003.

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The effects of single-trial averaging upon the spatial extent of fMRI activation

Cited by 87 publications

References 13 publications

Neural mechanisms involved in error processing: A comparison of errors made with and without awareness

Neural mechanisms involved in error processing: A comparison of errors made with and without awareness

Interference control during recognition of facial affect enhances the processing of expression specific properties — An event-related fMRI study

Stimulus repetition and hemodynamic response refractoriness in event‐related fMRI

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