Poster A90, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
Structure-Function Correlates of Successful Associative Encoding – A Multimodal Imaging Approach.
Nina Becker1,2, Grégoria Kalpouzos2, Alireza Salami2, Erika J. Laukka2, Yvonne Brehmer1,2; 1Otto Hahn Group on Associative Memory, Max Planck Institute for Human Development, Berlin, Germany, 2Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden
Functional magnetic resonance imaging (MRI) studies have demonstrated a critical role of hippocampus and inferior frontal gyrus (IFG) in successful associative encoding. Similarly, structural MRI studies have reported a positive relationship between associative memory and gray-matter (GM) volume of hippocampus and prefrontal cortex. Here, we sought to identify covariance patterns of GM volume and brain activity related to successful associative encoding by fusing structural and functional MRI data. T1-weighted images (3T GE) were collected from 24 young adults (M = 24.9 years), and functional MRI was employed during encoding of object pairs. A subsequent recognition task tested participants’ memory performance. Unimodal analyses using voxel-based morphometry revealed that participants with better associative memory showed larger GM volume in left anterior hippocampus. Similarly, subsequent memory analysis revealed activity in left anterior hippocampus and IFG related to successful associative encoding. Using joint independent component (IC) analysis, we investigated whether functional activation patterns within the associative encoding circuit could be locally or distally accounted for by GM volume. Results revealed one IC that comprised a covariance pattern between GM volume in anterior hippocampus and encoding-related activity in IFG. These regions were largely overlapping with those identified in the unimodal analyses. Importantly, individual IC loadings were positively correlated with associative memory indicating that individuals with stronger structure-function association performed episodic encoding more efficiently. Our findings suggest that GM within the medial temporal lobe modulates distally distinct parts of the associative encoding circuit, and extend previous studies that demonstrated hippocampal-IFG functional connectivity during associative memory tasks.
Topic Area: LONG-TERM MEMORY: Episodic