Dissociating the effects of Sternberg working memory demands in prefrontal cortex

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

doi:10.1016/j.pscychresns.2006.08.002

« Previous Next »Psychiatry Research: Neuroimaging
Volume 154, Issue 2 , Pages 103-114, 28 February 2007

Dissociating the effects of Sternberg working memory demands in prefrontal cortex

Mario Altamura
- Department of Biomedical Sciences, Psychiatry Unit, University of Foggia, Italy
- Clinical Brain Disorders Branch, NIMH, Bldg. 10, Bethesda MD, USA
- Corresponding author. Department of Biomedical Sciences, Psychiatry Unit, University of Foggia, Italy. Tel./fax: +39 01139/0881 732285.
Brita Elvevåg
- Clinical Brain Disorders Branch, NIMH, Bldg. 10, Bethesda MD, USA
Giuseppe Blasi
- Clinical Brain Disorders Branch, NIMH, Bldg. 10, Bethesda MD, USA
- Department of Neurology and Psychiatry, University of Bari, Italy
Alessandro Bertolino
- Department of Neurology and Psychiatry, University of Bari, Italy
- Department of Neuroradiology, IRCCSS “Casa Sollievo della Sofferenza” San Giovanni Rotondo, Italy
Joseph H. Callicott
- Clinical Brain Disorders Branch, NIMH, Bldg. 10, Bethesda MD, USA
Daniel R. Weinberger
- Clinical Brain Disorders Branch, NIMH, Bldg. 10, Bethesda MD, USA
Venkata S. Mattay
- Clinical Brain Disorders Branch, NIMH, Bldg. 10, Bethesda MD, USA
Terry E. Goldberg
- Clinical Brain Disorders Branch, NIMH, Bldg. 10, Bethesda MD, USA

Received 14 May 2006; received in revised form 20 August 2006; accepted 22 August 2006.

Abstract

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.

Keywords: Functional magnetic resonance imaging, Load, Maintenance, Healthy adults