Online Availability of fMRI Results Images

Functional magnetic resonance imaging (fMRI) has dramatically improved the ability of neuroscientists to localize regional cerebral blood flow–related changes due to cognitive function (Logothetis, 2002; Mandzia & Black, 2001; D’Esposito, 2000). From early fMRI studies of the motor response (Rao et al., 1993) to more recent studies of high-level cognition in complex reasoning (Atherton, Zhuang, Bart, Hu, & He, 2003), the degree of sophistication in fMRI paradigm design and accompanying statistical methods have both increased and become more involved. This has contributed to the veritable explosion of fMRI data—with the amount from individual imaging studies, at times, rivaling those in many disciplines in biology or the physical sciences— where more and more researchers are collecting larger and richer fMRI data sets. To communicate their results in the peer-reviewed literature, researchers often have to make selective, sometimes subjective, decisions about which figures to include in their published articles. In particular, fMRI statistical results maps presented in published articles may have thresholds applied that may conceal real, albeit more subtle, effects. Tabular lists of activation local maxima are routinely reported but are unlikely to provide a complete representation of the overall pattern contained in the statistical activation map. Such choices are necessary, however, because the data from these large studies certainly cannot be included in the printed journal article. For example, in this issue of JOCN, Druzgal and D’Esposito (pp. 771–784) used event-related fMRI to examine the relative roles of the prefrontal cortex and the medial fusiform gyrus in the memory encoding and retrieval for human faces. They observed increases in activity in both prefrontal and fusiform areas with increasing memory load, but, in particular, they noted timing differences in peak activation between these two regions, which may suggest a context-specific information flow. Their results are of interest in the light of evidence from the nonhuman primate literature, suggesting that connectivity between neurons in these two regions mediates visual working memory and that a similar mechanism may be at work in humans. In most cases, though, the tables and images from an intriguing article like this one would be all the reader had available to evaluate the reported findings. This can be frustrating when a particular result is not clear or may be open to an alternative interpretation. How many times has someone commented in your lab meeting or journal club, ‘‘Well, I’m skeptical about that result . . . I’d sure like to see their data!’’ Of course, it is often not possible to obtain the image data due to sociological (the authors do not care to have their results scrutinized) or technological (the images have been archived on tape and are not accessible) reasons (Koslow, 2002). However, in a unique opportunity for brain researchers, Druzgal and D’Esposito have made the statistical results maps from their study directly available to readers through the fMRI Data Center (fMRIDC) web site (http://www.fmridc.org). The fMRIDC regularly obtains the statistical results images, as well as the raw-reconstructed and preprocessed functional and structural image data from the authors of cognitive imaging studies. Researchers interested in study data can request the entire study data set, but direct online access has not been readily available until now. This will be the first of many instances where fMRI results images are made directly available online from articles published in this, and perhaps, other journals where the complete study data are archived at the fMRIDC. Readers of these articles can view the unthresholded results images using a Web-enabled image browser, observe the effects of applying their own statistical thresholds, and download the statistical images themselves (in Analyze format) for the purposes of meta-analytic comparison with other studies or for inspection with sophisticated visualization techniques (for instance, via cortical flattening; Van Essen et al., 2001). Direct examination of these maps will permit readers to consider these results more deeply, posit alternative explanations, and generate testable hypotheses about brain function in a manner not possible from the graphics or local maxima tables contained in the published article alone. fMRI data from studies of cognitive function are an extensive source of information involving brain activity over space, time, and empirical dimensions. The analytic results of these data are often hard to fully appreciate solely on the basis of the published article. By making these results images available via the Internet, researchers and students will have more to examine and contemplate than just what you see printed in these pages. Indeed, as more researchers make their fMRI Dartmouth College, Hanover, NH