Does excessive memory load attenuate activation in the prefrontal cortex? Load-dependent processing in single and dual tasks: functional magnetic resonance imaging study.

Full Abstract

Functional magnetic resonance imaging was used to investigate the relationship between cortical activation and memory load in dual tasks. An n-back task at four levels of difficulty was used with auditory-verbal and visual-nonverbal material, performed separately as single tasks and simultaneously as dual tasks. With reference to single tasks, activation in the prefrontal cortex (PFC) commonly increases with incremental memory load, whereas for dual tasks it has been hypothesized previously that activity in the PFC decreases in the face of excessive processing demands, i.e., if the capacity of the working memory's central executive system is exceeded. However, our results show that during both single and dual tasks, prefrontal activation increases continuously as a function of memory load. An increase of prefrontal activation was observed in the dual tasks even though processing demands were excessive in the case of the most difficult condition, as indicated by behavioral accuracy measures. The hypothesis concerning the decrease in prefrontal activation could not be supported and was discussed in terms of motivation factors. Similar changes in load-dependent activation were observed in two other regions outside the PFC, namely in the precentral gyrus and the superior parietal lobule. The results suggest that excessive processing demands in dual tasks are not necessarily accompanied by a diminution in cortical activity.

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Author information

Author/s: Jaeggi, Susanne M (SM); Seewer, Ria (R); Nirkko, Arto C (AC); Eckstein, Doris (D); Schroth, Gerhard (G); Groner, Rudolf (R); Gutbrod, Klemens (K);

Affiliation: Department of Psychology, University of Bern, CH-3000 Bern 9, Switzerland. susanne.jaeggi(-atsign-)psy.unibe.ch

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: NeuroImage (Neuroimage), published in United States. (Language: eng)

Reference: 2003-Jun; vol 19 (issue 2 Pt 1) : pp 210-25

Dates: Created 2003/06/19; Completed 2003/08/26; Revised 2006/11/15;

PMID: 12814572, status: MEDLINE (last retrieval date: 11/6/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult
Attention - physiology
Brain Mapping
Cerebral Cortex - physiology
Color Perception - physiology
Female
Humans
Image Enhancement
Magnetic Resonance Imaging
Male

Male
Memory, Short-Term - physiology
Nerve Net - physiology
Oxygen Consumption
Pattern Recognition, Visual - physiology
Prefrontal Cortex - physiology
Reaction Time - physiology
Retention (Psychology) - physiology
Speech Perception - physiology
Verbal Learning - physiology

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