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

John D Ragland, Bruce I. Turetsky, Ruben C. Gur, Faith Gunning-Dixon, Travis Turner, Lee Schroeder, Robin Chan, Raquel E. Gur

Research output: Contribution to journalArticle

179 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)370-379
Number of pages10
JournalNeuropsychology
Volume16
Issue number3
DOIs
StatePublished - 2002
Externally publishedYes

ASJC Scopus subject areas

  • Biological Psychiatry
  • Neuropsychology and Physiological Psychology

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    Ragland, J. D., Turetsky, B. I., Gur, R. C., Gunning-Dixon, F., Turner, T., Schroeder, L., Chan, R., & Gur, R. E. (2002). Working memory for complex figures: An fMRI comparison of letter and fractal n-back tasks. Neuropsychology, 16(3), 370-379. https://doi.org/10.1037/0894-4105.16.3.370