Stable degenerate brain systems that underlie visual short-term memory across the adult lifespan
Poster No:
1333
Submission Type:
Abstract Submission
Authors:
Michelle Jansen1, Alireza Salami2, Fernando Martínez1, Daniel Mitchell3, . Cam-CAN3, Linda Geerligs1
Institutions:
1Donders Institute, Radboud University, Nijmegen, Gelderland, 2Karolinska Institutet & Umeå University, Stockholm, Stockholm, 3MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, Cambridgeshire
First Author:
Co-Author(s):
Daniel Mitchell
MRC Cognition and Brain Sciences Unit, University of Cambridge
Cambridge, Cambridgeshire
MRC Cognition and Brain Sciences Unit, University of Cambridge
Cambridge, Cambridgeshire
Introduction:
Cognitive task performance may be supported through multiple neural pathways, a concept referred to as "brain degeneracy" [1]. We used a novel approach to consider brain degeneracy during a visual short-term memory (VSTM) task across the adult lifespan. Here, we identified groups of participants whose VSTM performance was characterized by different brain activation patterns and investigated whether these groups differed in age, task performance, grey matter (GM), and white matter (WM) integrity.
Methods:
We analyzed data of 113 participants from the Cam-CAN cohort (47.8% female, mean age 52.66, SD = 17.99) [2]. Participants engaged in a VSTM fMRI paradigm [3]. Our effect of interest was the activation difference between the highest and the lowest memory load during the maintenance period.
To identify modules of brain regions that responded similarly to VSTM load across different participants, we applied consensus partitioning based on the Louvain modularity algorithm [4,5]. We chose the partition with the highest resemblance to earlier detected age-representative networks [6]. To find groups of participants who showed differential recruitment patterns of the resulting brain modules, latent profile analysis was applied using the residual activity in each brain module and overall network responsivity.
Group differences in age, task performance, GM volumes, and mean kurtosis were examined using Welch's ANOVA and pairwise t-tests, corrected for age, total GM, and total intracranial volume (ICV) where appropriate. Within group associations between brain activity and task performance were investigated with Pearson correlations, controlling for age and mean responsivity across all ROIs.
To identify modules of brain regions that responded similarly to VSTM load across different participants, we applied consensus partitioning based on the Louvain modularity algorithm [4,5]. We chose the partition with the highest resemblance to earlier detected age-representative networks [6]. To find groups of participants who showed differential recruitment patterns of the resulting brain modules, latent profile analysis was applied using the residual activity in each brain module and overall network responsivity.
Group differences in age, task performance, GM volumes, and mean kurtosis were examined using Welch's ANOVA and pairwise t-tests, corrected for age, total GM, and total intracranial volume (ICV) where appropriate. Within group associations between brain activity and task performance were investigated with Pearson correlations, controlling for age and mean responsivity across all ROIs.
Results:
We identified seven distinct brain modules that resembled earlier identified functional networks. A model with 4 latent groups resulted in the most optimal fit (n=35, n=24, n=42, n=12 in groups 1-4). Group differences were most evident for the frontal control module (FCM), visual module (VM), and default mode module (DMM; Fig 1).
Group 4 tended to be younger (group 1, p<0.01; group 2, p=0.03; group 3, p=0.06). Significant group differences were observed in mean kurtosis for the left uncinate fasciculus and the left inferior longitudinal fasciculus, after correcting for ICV (all p<0.001). Group 2, the subgroup with low FCM and high VM recruitment, showed reduced WM integrity in these tracts.
We observed negative associations between FCM activation and memory precision in group 1 and 2 (r=-0.46, p=0.006; r=-0.41, p=0.055). Notably, these groups also showed lower levels of FCM recruitment during the task. Further, we noted a negative association between activity in the DMN and the number of items in memory in group 1 (r=-0.35, p=0.045), suggesting that the reduced DMN suppression in this group was negatively affecting performance.
Group 4 tended to be younger (group 1, p<0.01; group 2, p=0.03; group 3, p=0.06). Significant group differences were observed in mean kurtosis for the left uncinate fasciculus and the left inferior longitudinal fasciculus, after correcting for ICV (all p<0.001). Group 2, the subgroup with low FCM and high VM recruitment, showed reduced WM integrity in these tracts.
We observed negative associations between FCM activation and memory precision in group 1 and 2 (r=-0.46, p=0.006; r=-0.41, p=0.055). Notably, these groups also showed lower levels of FCM recruitment during the task. Further, we noted a negative association between activity in the DMN and the number of items in memory in group 1 (r=-0.35, p=0.045), suggesting that the reduced DMN suppression in this group was negatively affecting performance.
·Figure 1
Conclusions:
We identified groups of participants that were characterized by different brain activation patterns. These groups did not differ in task performance, but were characterized by differential associations between brain activity and performance, particularly in the FCM. We also observed age-independent differences in WM integrity between groups, particularly in the uncinate fasciculus. This suggests that differences in brain activity during task performance might have been shaped by individual differences in brain structure.
Individuals can use different cognitive strategies to complete the VSTM task (e.g., verbalizing the memory representation or visualizing the items) [7]. Notably, the uncinate fasciculus has been implicated in semantic language processing, associative learning, and working memory. We could speculate that group 2 relied more on maintaining visual representations by recruiting the VM due to the reduced integrity in the left uncinate fasciculus.
Altogether, our novel analysis approach may help to further understand how multiple neural pathways could underlie cognitive performance.
Individuals can use different cognitive strategies to complete the VSTM task (e.g., verbalizing the memory representation or visualizing the items) [7]. Notably, the uncinate fasciculus has been implicated in semantic language processing, associative learning, and working memory. We could speculate that group 2 relied more on maintaining visual representations by recruiting the VM due to the reduced integrity in the left uncinate fasciculus.
Altogether, our novel analysis approach may help to further understand how multiple neural pathways could underlie cognitive performance.
Learning and Memory:
Working Memory
Lifespan Development:
Aging 2
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI) 1
Methods Development
Novel Imaging Acquisition Methods:
Multi-Modal Imaging
Keywords:
Cognition
Data analysis
FUNCTIONAL MRI
MRI
STRUCTURAL MRI
White Matter
1|2Indicates the priority used for review
Provide references using author date format
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