Dissociating the effects of Sternberg working memory demands in prefrontal cortex

Mario Altamura, Brita Elvevåg, Giuseppe Blasi, Alessandro Bertolino, Joseph H. Callicott, Daniel R. Weinberger, Venkata S. Mattay, Terry E. Goldberg

Research output: Contribution to journalArticlepeer-review


Earlier neuroimaging studies of working memory (WM) have demonstrated that dorsolateral prefrontal cortex (DLPFC) activity increases as maintenance and load demand increases. However, few studies have carefully disambiguated these two WM processes at the behavioral and physiological levels. The objective of the present functional resonance imaging (fMRI) study was to map within prefrontal cortex locales that are selectively load sensitive, delay sensitive, or both. We studied 18 right-handed normal subjects with fMRI at 3 Tesla during a block design version of the Sternberg task. WM load was manipulated by varying the memory set size (3, 5, or 8 letters). The effect of memory maintenance was examined by employing two time delays (1 s and 6 s) between the letter set and probe stimuli. The DLPFC was strongly activated in load manipulation, whereas activation as a function of delay was restricted to the left premotor regions and Broca's areas. Moreover, regions of prefrontal cortex on the right (BA 46) were found to be exclusively affected by load. These results suggest the possibility that top-down modulation of attention or cognitive control at encoding and/or decisionmaking may be mediated by these areas.

Original languageEnglish
Pages (from-to)103-114
Number of pages12
JournalPsychiatry Research - Neuroimaging
Issue number2
Publication statusPublished - Feb 28 2007


  • Functional magnetic resonance imaging
  • Healthy adults
  • Load
  • Maintenance

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Radiology Nuclear Medicine and imaging
  • Biological Psychiatry
  • Psychology(all)


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