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Age-related changs in the neural correlates of working memory: a fMRI study
NemoImage
13, Number
6, 2001, Part 2 of 2 Parts 1 D E b
L@
ATTENTION
Age-related changes in the neural correlates of working memory : a fMR1 study Assia SERRADJ JAILLARD*, Marc HOMMEL*, Jean Luc ROULIN?, Chantal DELON MARTIN& Jean Fraqois LEBASS, Jean Fraqois LEBASS, Christoph Segehartht *Neurology TLaboratoire
de Psychologie $CEA
CHU
GRenoble
Expe’rimentale UJF INSERM
$Neuroradiologie
France
Universite’ U438 Grenoble
CHU Grenoble
de Savoie
Chambe’ry
France
France France
Introduction Functional neuroimaging studies of working memory have shown reliable activation of frontal cortex (1, 2). Ageing effects have been reported during cognitive tasks (3,4). The aim of this study was lo examine the ageing effects on frontal activation in a WM paradigm. Subjects
and methods
Twenty healthy subjects, 10 aged between 25 and 47 (the younger group), and 10 between 60 and 65 (the older group), were examined. Both groups were matched for educational level. A block design was applied which was composed of 5 task and 5 control conditions (30s each, 5 min overall). During the task conditions, subjects were presented (1) a sequence of 4 or 5 single digit stimuli (3 or 2.4 set presentation time per stimulus, respectively), followed by (2) a delay period of 6 set and (3) by a sequence of 4 two- or three-digit target numbers (3 set presentation time each). Subjects were instructed to recall the first and every two digit stimuli in inverse order (i.e. 923 for the sequence 3 7 2 4 9) and then to select the corresponding target number by pressing a button). During the control conditions, subjects were presented (1) a sequence of 5 sequentially presented target single signs, (2) a delay period and (3) 3 single sign targets and one double sign target. Timing was similar as during the task conditions. Subjects were instructed to select the double sign target. Subjects were extensively trained. Imaging was done at 1.5T with a GRE EPI sequence (TR=3.3s, TE=45msec, 28 contiguous slices (5mm each) were acquired parallel to the AC-PC line). A group analysis was performed with SPM99 (p=O.O5 corrected). Results Reaction times differed significantly between the two groups, but performances from 10 subjects. In the younger (Y) group (6 subjects), activations were found 46, 6, left BA 45), in the right parietal cortex (BA 7) and the left cerebellum. In found in the same areas. Furthermore, bilateral inferior (BA 44, 45,46), middle parietal areas ( BA 7, 39, 40) were activated. The contrast (O-Y) revealed bilateral activation of prefrontal areas (BA 6 and posterior regions (left BA 19 and right BA 7) and of right cerebellum. Figl.
did not. Preliminary results have been obtained in the bilateral prefrontal cortex (right BA 9, 44, the older (0) group (4 subjects), activations were frontal (BA6, 9), right temporal (BA 21. 37) and 46 bilaterally,
left BA 9, right BA 44 and 45), of
Conclusions These preliminary results show activation foci associated in several previous WM studies with the manipulation and the storage of verbal components. An ageing effect has been found. The recruitment of additional prefrontal areas may be related to the additional recruitment observed when the WM load is increased (5). These results may reflect age-related plasticity. References 1. 2. 3. 4. 5.
Koechlin E et al, Nature 399:148 (1999). Smith EE, Jonides J. Science 283:1657 (1999). d’Esposito G et al, Brain 122:963 (1999). Leonards U et al, Soc.Neurosci.Abstr. 26(2):23 Rypma B et al, Neuroimage 9:216 (1999).
(2000).
s357
13, Number
6, 2001, Part 2 of 2 Parts 1 D E b
L@
ATTENTION
Age-related changes in the neural correlates of working memory : a fMR1 study Assia SERRADJ JAILLARD*, Marc HOMMEL*, Jean Luc ROULIN?, Chantal DELON MARTIN& Jean Fraqois LEBASS, Jean Fraqois LEBASS, Christoph Segehartht *Neurology TLaboratoire
de Psychologie $CEA
CHU
GRenoble
Expe’rimentale UJF INSERM
$Neuroradiologie
France
Universite’ U438 Grenoble
CHU Grenoble
de Savoie
Chambe’ry
France
France France
Introduction Functional neuroimaging studies of working memory have shown reliable activation of frontal cortex (1, 2). Ageing effects have been reported during cognitive tasks (3,4). The aim of this study was lo examine the ageing effects on frontal activation in a WM paradigm. Subjects
and methods
Twenty healthy subjects, 10 aged between 25 and 47 (the younger group), and 10 between 60 and 65 (the older group), were examined. Both groups were matched for educational level. A block design was applied which was composed of 5 task and 5 control conditions (30s each, 5 min overall). During the task conditions, subjects were presented (1) a sequence of 4 or 5 single digit stimuli (3 or 2.4 set presentation time per stimulus, respectively), followed by (2) a delay period of 6 set and (3) by a sequence of 4 two- or three-digit target numbers (3 set presentation time each). Subjects were instructed to recall the first and every two digit stimuli in inverse order (i.e. 923 for the sequence 3 7 2 4 9) and then to select the corresponding target number by pressing a button). During the control conditions, subjects were presented (1) a sequence of 5 sequentially presented target single signs, (2) a delay period and (3) 3 single sign targets and one double sign target. Timing was similar as during the task conditions. Subjects were instructed to select the double sign target. Subjects were extensively trained. Imaging was done at 1.5T with a GRE EPI sequence (TR=3.3s, TE=45msec, 28 contiguous slices (5mm each) were acquired parallel to the AC-PC line). A group analysis was performed with SPM99 (p=O.O5 corrected). Results Reaction times differed significantly between the two groups, but performances from 10 subjects. In the younger (Y) group (6 subjects), activations were found 46, 6, left BA 45), in the right parietal cortex (BA 7) and the left cerebellum. In found in the same areas. Furthermore, bilateral inferior (BA 44, 45,46), middle parietal areas ( BA 7, 39, 40) were activated. The contrast (O-Y) revealed bilateral activation of prefrontal areas (BA 6 and posterior regions (left BA 19 and right BA 7) and of right cerebellum. Figl.
did not. Preliminary results have been obtained in the bilateral prefrontal cortex (right BA 9, 44, the older (0) group (4 subjects), activations were frontal (BA6, 9), right temporal (BA 21. 37) and 46 bilaterally,
left BA 9, right BA 44 and 45), of
Conclusions These preliminary results show activation foci associated in several previous WM studies with the manipulation and the storage of verbal components. An ageing effect has been found. The recruitment of additional prefrontal areas may be related to the additional recruitment observed when the WM load is increased (5). These results may reflect age-related plasticity. References 1. 2. 3. 4. 5.
Koechlin E et al, Nature 399:148 (1999). Smith EE, Jonides J. Science 283:1657 (1999). d’Esposito G et al, Brain 122:963 (1999). Leonards U et al, Soc.Neurosci.Abstr. 26(2):23 Rypma B et al, Neuroimage 9:216 (1999).
(2000).
s357