Monday, September 8, 2014

nice methods: Manelis and Reder 2013, "He Who is Well Prepared ..."

It's always great to read a paper with interesting methodology clearly explained, and Manelis and Reder 2013, "He Who Is Well Prepared Has Half Won The Battle: An fMRI Study of Task Preparation" is one of those papers (full citation below). As usual, I'm not going to fully describe the paper (go read it!), but just comment on a few things that caught my eye.

First, I was struck again by the strength and consistency of the activations and deactivations associated with the n-back task; they seem as reliable as those from some motor and somatosensory tasks. The authors used a mass-univariate analysis to identify a set of ROIs to use for the MVPA, shown in this part of Figure 2 (warm colors for regions that increased with n-back level, and cool colors for regions that decreased). As the authors properly point out, doing MVPA on the task blocks with these ROIs would be somewhat circular (since a mass-univariate analysis of the task blocks was used to create the ROIs), but their main MVPA avoids circularity, since it was done on a different part of the task.

Next, I appreciated the discussions of possible confounds in the results section: the authors report pairwise accuracies, not just the three-way, explaining that they want to make sure one very accurate pair is not driving the results, and they performed a nice control analysis using randomly-selected rest volumes.

Finally, they found a correlation between classification accuracy (MVPA during task preparation periods) and behavioral performance (participant speed on the n-back task); there are still relatively few reports tying fMRI analyses to behavior, and it's nice to see another one.

ResearchBlogging.orgManelis, A., & Reder, L. (2013). He Who Is Well Prepared Has Half Won The Battle: An fMRI Study of Task Preparation Cerebral Cortex DOI: 10.1093/cercor/bht262

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