Dyslexic Children Show Short-Term Memory Deficits in Phonological Storage and Serial Rehearsal: An fMRI Study
Authors:
Harald Beneventi a;
Finn Egil T
nnessen b;
Lars Ersland cd
nnessen b;
Lars Ersland cd
| Affiliations: | a Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway |
| b Department of Education, Center for Reading Research, University of Stavanger, Stavanger, Norway | |
| c Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway | |
| d Department of Surgical Science, University of Bergen, Bergen, Norway |
DOI:
10.1080/00207450903139671
Publication Frequency:
12 issues per year
Published in:
International Journal of Neuroscience,
Volume
119,
Issue
11
November
2009
, pages 2017
- 2043
Subject:
Neuroscience;
Full text options: no full text options are available.
Abstract
Dyslexia is primarily associated with a phonological processing deficit. However, the clinical manifestation also includes a reduced verbal working memory (WM) span. It is unclear whether this WM impairment is caused by the phonological deficit or a distinct WM deficit. The main aim of this study was to investigate neuronal activation related to phonological storage and rehearsal of serial order in WM in a sample of 13-year-old dyslexic children compared with age-matched nondyslexic children. A sequential verbal WM task with two tasks was used. In the Letter Probe task, the probe consisted of a single letter and the judgment was for the presence or absence of that letter in the prior sequence of six letters. In the Sequence Probe (SP) task, the probe consisted of all six letters and the judgment was for a match of their serial order with the temporal order in the prior sequence. Group analyses as well as single-subject analysis were performed with the statistical parametric mapping software SPM2. In the Letter Probe task, the dyslexic readers showed reduced activation in the left precentral gyrus (BA6) compared to control group. In the Sequence Probe task, the dyslexic readers showed reduced activation in the prefrontal cortex and the superior parietal cortex (BA7) compared to the control subjects. Our findings suggest that a verbal WM impairment in dyslexia involves an extended neural network including the prefrontal cortex and the superior parietal cortex. Reduced activation in the left BA6 in both the Letter Probe and Sequence Probe tasks may be caused by a deficit in phonological processing. However, reduced bilateral activation in the BA7 in the Sequence Probe task only could indicate a distinct working memory deficit in dyslexia associated with temporal order processing.
|
| Keywords: dyslexia; fMRI; phonological storage; serial rehearsal; short-term memory; working memory |
| view references (47) |


Download Citation

CiteULike
Del.icio.us
BibSonomy
Connotea