Uncoupling cognitive workload and prefrontal cortical physiology: A PET rCBF study

Terry E. Goldberg, Karen Faith Berman, Kirsten Fleming, Jill Ostrem, John D. Van Horn, Giuseppe Esposito, Venkata S. Mattay, James M. Gold, Daniel R. Weinberger

Research output: Contribution to journalArticlepeer-review


Working memory is a fundamental cognitive building block involved in the short-term maintenance and transformation of information. In neuropsychological studies, working memory has been shown to be of limited capacity; however, the neurophysiological concomitants of this capacity limitation have not been explored. In this study we used the [15O]water PET rCBF technique and statistical parametric mapping to examine normal subjects while they performed two cognitive tasks, both individually and simultaneously. One task was the Wisconsin Card Sorting Test, a complex reasoning task involving working memory, and the other was a rapidly paced auditory verbal shadowing task. When both tasks were performed simultaneously, there were significant decrements in performance compared with the individual task performance scores, indicating that cognitive workload had been increased. Analysis of the rCBF maps showed that when the two tasks were performed together, in contrast to when they were performed separately, there was less prefrontal activation. These results suggest that increases in cognitive workload do not necessarily recruit and then sustain cortical neurophysiological resources to a maximum, but rather may actually be accompanied by a diminution in cortical activity.

Original languageEnglish (US)
Pages (from-to)296-303
Number of pages8
Issue number4 I
StatePublished - May 1998
Externally publishedYes


  • Cognition
  • Dual task
  • Frontal lobe
  • Humans
  • PET
  • Working memory

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience


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