Journal ArticleDOI
Event-Related fMRI: Characterizing Differential Responses
Karl J. Friston,Paul C. Fletcher,Oliver Josephs,Andrew P. Holmes,Michael D. Rugg,Michael D. Rugg,Robert Turner +6 more
TLDR
This paper focuses on bilateral ventrolateral prefrontal responses that show deactivations for previously seen words and activations for novel words in functional magnetic resonance imaging that are evoked by different sorts of stimuli.Citations
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Journal ArticleDOI
The neural mechanisms of top-down attentional control.
TL;DR: FMRI was used during a cued spatial-attention task to dissociate brain activity related to attentional control from that related to selective processing of target stimuli, indicating that Superior frontal, inferior parietal and superior temporal cortex were selectively activated by cues.
Journal ArticleDOI
Somatotopic Representation of Action Words in Human Motor and Premotor Cortex
TL;DR: It is demonstrated that the referential meaning of action words has a correlate in the somatotopic activation of motor and premotor cortex, which rules out a unified "meaning center" in the human brain and supports a dynamic view according to which words are processed by distributed neuronal assemblies with cortical topographies that reflect word semantics.
Journal ArticleDOI
Optimal experimental design for event-related fMRI.
TL;DR: A quantitative analysis of the relative efficiency afforded by different event‐related experimental designs shows that statistical efficiency falls off dramatically as the ISI gets sufficiently short, if the ISI is kept fixed for all trials, but improves monotonically with decreasing mean ISI.
Journal ArticleDOI
Dynamic Statistical Parametric Mapping: Combining fMRI and MEG for High-Resolution Imaging of Cortical Activity
Anders M. Dale,Arthur K. Liu,Bruce Fischl,Randy L. Buckner,John W. Belliveau,Jeffrey D. Lewine,Eric Halgren,Eric Halgren,Eric Halgren +8 more
TL;DR: A technique that combines structural and functional MRI with magnetoencephalography (MEG) to obtain spatiotemporal maps of human brain activity with millisecond temporal resolution was used to obtain dynamic statistical parametric maps of cortical activity during semantic processing of visually presented words.
Journal ArticleDOI
Interpreting the BOLD signal.
TL;DR: The current understanding of the causal relationships between neural activity and the blood-oxygen-level-dependent (BOLD) signal is described, and how these analyses have challenged some basic assumptions that have guided neuroscience are reviewed.
References
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Journal ArticleDOI
Spatial registration and normalization of images
Karl J. Friston,John Ashburner,Chris D. Frith,Jean-Baptiste Poline,Jon D. Heather,Richard S. J. Frackowiak +5 more
TL;DR: A general technique that facilitates nonlinear spatial (stereotactic) normalization and image realignment is presented that minimizes the sum of squares between two images following non linear spatial deformations and transformations of the voxel (intensity) values.
Journal ArticleDOI
Speed of processing in the human visual system.
TL;DR: The visual processing needed to perform this highly demanding task can be achieved in under 150 ms, and ERP analysis revealed a frontal negativity specific to no-go trials that develops roughly 150 ms after stimulus onset.
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Movement-related effects in fMRI time-series
TL;DR: The empirical analyses suggest that (in extreme situations) over 90% of fMRI signal can be attributed to movement, and that this artifactual component can be successfully removed.
Journal ArticleDOI
Analysis of fMRI Time-Series Revisited
Karl J. Friston,Andrew P. Holmes,Jean-Baptiste Poline,P. J. Grasby,Steven Williams,Richard S. J. Frackowiak,Robert Turner +6 more
TL;DR: The approach is predicated on an extension of the general linear model that allows for correlations between error terms due to physiological noise or correlations that ensue after temporal smoothing, and uses the effective degrees of freedom associated with the error term.
Journal ArticleDOI
Linear Systems Analysis of Functional Magnetic Resonance Imaging in Human V1
TL;DR: Results from three empirical tests support the hypothesis that fMRI responses in human primary visual cortex (V1) depend separably on stimulus timing and stimulus contrast, and the noise in the fMRI data is independent of stimulus contrast and temporal period.