Working memory for complex figures: an fMRI comparison of letter and fractal n-back tasks.

Publication Type	Academic Article
Authors	Ragland J, Turetsky B, Gur R, Gunning-Dixon F, Turner T, Schroeder L, Chan R, Gur R
Journal	Neuropsychology
Volume	16
Issue	3
Pagination	370-9
Date Published	07/01/2002
ISSN	0894-4105
Keywords	Brain, Magnetic Resonance Imaging, Memory
Abstract	n-back letter and fractal tasks were administered to 11 participants during functional magnetic resonance imaging to test process specificity theories of prefrontal cortex (PFC) function and assess task validity. Tasks were matched on accuracy, but fractal n-back responses were slower and more conservative. Maintenance (1-back minus 0-back) activated inferior parietal and dorsolateral PFC, with additional activation in right ventrolateral PFC during letter n-back and left lingual gyrus during fractal n-back. Maintenance plus manipulation (2-back minus 0-back) activated inferior parietal, Broca's area, insula, and dorsolateral and ventral PFC, with greater right dorsolateral PFC activation for letter n-back. Manipulation only (2-back minus 1-back) produced additional and equivalent dorsolateral PFC and anterior cingulate activation in both tasks. Results support fractal n-back validity and indicate substantial overlap in working memory functions of dorsal and ventral PFC.
PubMed ID	12146684
PubMed Central ID	PMC4332798