Working memory for letters, shapes, and locations: fMRI evidence against stimulus-based regional organization in human prefrontal cortex.

@article{citeulike:1298481, abstract = {Investigations of working memory (WM) systems in the frontal cortex have revealed two stimulus dimensions along which frontal cortical representations may be functionally organized. One hypothesized dimension dissociates verbal from nonverbal WM processes, dividing left from right frontal regions. The second hypothesized dimension dissociates spatial from nonspatial WM, dividing dorsal from ventral frontal regions. Here we used functional magnetic resonance imaging to probe WM processes associated with three different types of stimuli: letters (verbal and nonspatial), abstract shapes (nonverbal and nonspatial), and locations (nonverbal and spatial). In a series of three experiments using the "n-back" WM paradigm, direct statistical comparisons were made between activation patterns in each pairwise combination of the three stimulus types. Across the experiments, no regions that demonstrated responses to WM manipulations were discovered to be unique to any of the three stimulus types. Therefore, no evidence was found to support either a left/right verbal/nonverbal dissociation or a dorsal/ventral spatial/nonspatial dissociation. While this could reflect a limitation of the present behavioral and imaging techniques, other factors that could account for the data are considered, including subjects' strategy selection, encoding of information into WM, and the nature of representational schemes in prefrontal cortex.}, address = {Department of Psychology, Princeton University, Princeton, New Jersey 08544, USA.}, author = {Nystrom, L. E. and Braver, T. S. and Sabb, F. W. and Delgado, M. R. and Noll, D. C. and Cohen, J. D. }, citeulike-article-id = {1298481}, doi = {10.1006/nimg.2000.0572}, issn = {1053-8119}, journal = {Neuroimage}, keywords = {fmri, hu, nback, workingmemory}, month = {May}, number = {5 Pt 1}, pages = {424--446}, posted-at = {2008-01-02 22:59:35}, priority = {2}, title = {Working memory for letters, shapes, and locations: fMRI evidence against stimulus-based regional organization in human prefrontal cortex.}, url = {http://dx.doi.org/10.1006/nimg.2000.0572}, volume = {11}, year = {2000} }

TY - JOUR ID - citeulike:1298481 L3 - citeulike-article-id:1298481 TI - Working memory for letters, shapes, and locations: fMRI evidence against stimulus-based regional organization in human prefrontal cortex. JF - Neuroimage VL - 11 IS - 5 Pt 1 SP - 424 EP - 446 AD - Department of Psychology, Princeton University, Princeton, New Jersey 08544, USA. SN - 1053-8119 N2 - Investigations of working memory (WM) systems in the frontal cortex have revealed two stimulus dimensions along which frontal cortical representations may be functionally organized. One hypothesized dimension dissociates verbal from nonverbal WM processes, dividing left from right frontal regions. The second hypothesized dimension dissociates spatial from nonspatial WM, dividing dorsal from ventral frontal regions. Here we used functional magnetic resonance imaging to probe WM processes associated with three different types of stimuli: letters (verbal and nonspatial), abstract shapes (nonverbal and nonspatial), and locations (nonverbal and spatial). In a series of three experiments using the "n-back" WM paradigm, direct statistical comparisons were made between activation patterns in each pairwise combination of the three stimulus types. Across the experiments, no regions that demonstrated responses to WM manipulations were discovered to be unique to any of the three stimulus types. Therefore, no evidence was found to support either a left/right verbal/nonverbal dissociation or a dorsal/ventral spatial/nonspatial dissociation. While this could reflect a limitation of the present behavioral and imaging techniques, other factors that could account for the data are considered, including subjects' strategy selection, encoding of information into WM, and the nature of representational schemes in prefrontal cortex. KW - fmri KW - hu KW - nback KW - workingmemory AU - Nystrom, LE AU - Braver, TS AU - Sabb, FW AU - Delgado, MR AU - Noll, DC AU - Cohen, JD PY - 2000/05// UR - http://dx.doi.org/10.1006/nimg.2000.0572 ER -