A critique of functional localisers

The Wellcome Department of Imaging Neuroscience, Institute of Neurology, UCL, 12 Queen Square, London WC1N 3BG, UK.
NeuroImage (Impact Factor: 6.36). 06/2006; 30(4):1077-87. DOI: 10.1016/j.neuroimage.2005.08.012
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ABSTRACT In this critique, we review the usefulness of functional localising scans in functional MRI studies. We consider their conceptual motivations and the implications for experimental design and inference. Functional localisers can often be viewed as acquiring data from cells that have been removed from an implicit factorial design. This perspective reveals their potentially restrictive nature. We deconstruct two examples from the recent literature to highlight the key issues. We conclude that localiser scans can be unnecessary and, in some instances, lead to a biased and inappropriately constrained characterisation of functional anatomy.

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Available from: Pia Rotshtein, Jul 28, 2015
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    • "there was one interaction effect whose test was motivated by the behavioural results, namely a hand-by-view interaction. to provide a realistic protection against false positives in these higher-level interaction effect (given the presence of a baseline at the first level, the view-by-hand interactions are second-level interactions), we used a smallvolume correction constrained by the functional localizer of the main effect of the palm-minus-back view (see Friston et al. 2006): the small-volume correction for this interaction effect was calculated using a 10-mm-radius sphere centred on two local maxima identified by the functional localizer. "
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    Experimental Brain Research 08/2014; 232(12). DOI:10.1007/s00221-014-4065-z · 2.17 Impact Factor
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    • "As the above localization analyses were based on BOLD signal averaged across all block-related conditions (attention left vs. right, and grouped vs. ungrouped) this method of localization could not bias the outcome of our tests for hypothesized differences between conditions, either block-related or event-related. This method of defining a region of interest, based on a contrast that is orthogonal to those used to test an experimental hypothesis , is an established approach in the literature (Friston et al., 2006). We used our own circularly translating stimuli, rather than a traditional independent motion localizer based on moving random-dot kinematograms, as this could isolate regions sensitive to the specific type of motion used in our main experiment , providing a principled and statistically independent way to identifying relevant voxels that might be subject to our particular modulations of spatial attention and stimulus grouping. "
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    Frontiers in Integrative Neuroscience 02/2014; 8:12. DOI:10.3389/fnint.2014.00012
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