Dissociating working memory from task difficulty in human prefrontal cortex

Deanna M. Barch, Todd S. Braver, Leigh E. Nystrom, Steven D. Forman, Douglas C. Noll, Jonathan D. Cohen

Research output: Contribution to journalArticlepeer-review

511 Scopus citations


A functional magnetic resonance imaging (fMRI) study was conducted to determine whether prefrontal cortex (PFC) increases activity in working memory (WM) tasks as a specific result of the demands placed on WM, or to other processes affected by the greater difficulty of such tasks. Increased activity in dorsolateral PFC (DLPFC) was observed during task conditions that placed demands on active maintenance (long retention interval) relative to control conditions matched for difficulty. Furthermore, the activity was sustained over the entire retention interval and did not increase when task difficulty was manipulated independently of WM requirements. This contrasted with the transient increases in activity observed in the anterior cingulate, and other regions of frontal cortex, in response to increased task difficulty but not WM demands. Thus, this study established a double-dissociation between regions responsive to WM versus task difficulty, indicating a specific involvement of DLPFC and related structures in WM function.

Original languageEnglish (US)
Pages (from-to)1373-1380
Number of pages8
Issue number10
StatePublished - Oct 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience
  • Behavioral Neuroscience


  • Anterior cingulate
  • Broca's area
  • Continuous performance test
  • Neuroimaging
  • Parietal cortex
  • Task difficulty


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