Hippocampal and precuneus structural changes are linked to mnemonic discrimination training gains
Poster No:
853
Submission Type:
Abstract Submission
Authors:
Panagiotis Iliopoulos1, Helena Gellersen2, Boyan Rong1, Anne Maass3, Radoslaw Martin Cichy4, Emrah Düzel2
Institutions:
1Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany, 2German Center for Neurodegenerative Diseases, Magdeburg, Sachsen-Anhalt, 3German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany, 4Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany
First Author:
Panagiotis Iliopoulos
Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University
Magdeburg, Germany
Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University
Magdeburg, Germany
Co-Author(s):
Boyan Rong
Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University
Magdeburg, Germany
Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University
Magdeburg, Germany
Radoslaw Martin Cichy
Department of Education and Psychology, Freie Universität Berlin
Berlin, Germany
Department of Education and Psychology, Freie Universität Berlin
Berlin, Germany
Introduction:
Successful memory requires distinguishing between similar information, a process referred to as mnemonic discrimination. While episodic memory declines in old age, this decline may be attenuated via cognitive training. However, the scope of improvement in older adults' cognitive performance and brain structural plasticity following cognitive training is poorly understood. The hippocampus, particularly its subfields such as CA3, plays a crucial role in supporting MD. Standard imaging techniques at 3T often lack the resolution to investigate such subfield-specific contributions. By leveraging high-resolution 7T MRI, this study was able to hone in on subtle structural changes in hippocampal subfields that may underlie training-related cognitive improvements. To address these gaps, we investigated whether cognitive training leads to improvement in MD and if these gains are linked to structural changes in key hippocampal and cortical regions.
Methods:
A total of 151 cognitively healthy older adults (age M = 69.71 years, SD = 4.17) completed an 8-week web-based MD training intervention. Participants were divided into three groups: one group training with object stimuli (OG = object group), one group training with scene stimuli (SG = scene group), and one active control group (AC). A subset of participants in OG (n = 33) and AC (n = 28) also underwent pre- and post-training 7T MR imaging (T1w: 0.6 mm iso). The training paradigm involved differentiating similar objects and scenes ('lures'; correct response: 'new') from repeated items ('repeats', correct response: 'old'). Stimuli were first presented in a 2-back set-size, where the first two stimuli were new images, while each of the subsequent two could be either a lure or a repeat trial. The set-size increased progressively throughout the training based on participants' performance. Pre- and post-training, all participants performed a behavioral session that included the 2-back object-scene MD task and several additional cognitive tasks to assess transfer effects, which among others included the mnemonic similarity task (MST (Stark et al., 2019); a similar task requiring MD for objects). To calculate gray matter and cortical folding changes (gyrification: absolute mean curvature of the central surface) the CAT12 longitudinal plasticity pipeline was used.
Results:
Training improved MD performance (group x time: F(136,2) = 7.35, p < .001). OG participants showed enhanced object MD (t(137) = 5.55, p < .001) and evidence of near transfer to scenes, while SG participants improved only in scene MD (t(137) = 6.02, p < .001). Linear models on change scores revealed that MD performance gains in OG participants were associated with post-training increased gray matter volume in the hippocampal left CA2-3 region and cortical gyrification in the precuneus (Fig. 1). These findings suggest broader neural adaptations beyond the hippocampus, involving structural changes in the precuneus that may support cognitive training-induced improvements
Conclusions:
Our findings demonstrate that cognitive training can enhance mnemonic discrimination in older adults, with structural plasticity emerging as a potential underlying mechanism. Specifically, improvements in MD performance were linked to increased gray matter volume in the hippocampal CA2-3 region and cortical gyrification in the precuneus. The use of 7T MRI enabled high-resolution insights into the hippocampal subfields, allowing us to identify the CA2-3 as a key region linked to MD post-training gains. While the hippocampus is well-known for its role in pattern separation, the involvement of the precuneus, which is a highly connected hub region supporting episodic memory, highlights the contribution of cortical regions in supporting training-induced memory improvements. These results provide evidence for both localized and distributed neural plasticity in response to cognitive training and underscore the potential of targeted interventions to mitigate age-related cognitive decline.
Learning and Memory:
Long-Term Memory (Episodic and Semantic) 1
Neural Plasticity and Recovery of Function 2
Keywords:
Memory
Plasticity
STRUCTURAL MRI
Other - Cognitive Training
1|2Indicates the priority used for review
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Were any human subjects research approved by the relevant Institutional Review Board or ethics panel? NOTE: Any human subjects studies without IRB approval will be automatically rejected.
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Provide references using APA citation style.
Gaser, C., Dahnke, R., Thompson, P. M., Kurth, F., Luders, E., & Alzheimer's Disease Neuroimaging Initiative. (2024). CAT: a computational anatomy toolbox for the analysis of structural MRI data. GigaScience, 13, giae049.
Luders, E., Thompson, P. M., Narr, K. L., Toga, A. W., Jancke, L., & Gaser, C. (2006). A curvature-based approach to estimate local gyrification on the cortical surface. Neuroimage, 29(4), 1224-1230. https://doi.org/10.1016/j.neuroimage.2005.08.049.
Stark, S. M., Kirwan, C. B., & Stark, C. E. L. (2019). Mnemonic Similarity Task: A Tool for Assessing Hippocampal Integrity. Trends in Cognitive Sciences, 23(11), 938–951. https://doi.org/10.1016/j.tics.2019.08.003