Poster D2, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Structural and functional evidence for thalamic nucleus reuniens in the human brain
Zachariah Reagh1, Aaron Mattfeld2, Timothy Allen2, Maria Montchal1, Michael Yassa1; 1University of California, Irvine, 2Florida International University
Recently, memory researchers have taken great interest in interactions among the hippocampus (HC) and association areas of the neocortex. A major area of interest is the relationship between HC and medial prefrontal cortex (mPFC). One hypothesis states that mPFC organizes HC-dependent memories into conceptual frameworks. Another hypothesis states that mPFC aids in directed recall by selecting 'appropriate' HC-dependent memories in a given context. There are a few distinct anatomical routes from mPFC to HC, most prominently through thalamic nucleus reuniens (NR). Recent studies in rodents have found that NR is crucial for HC-mPFC interactions, as well as aspects of memory and navigation. However, NR and its role in cognition remain unexplored in humans. Here, we present diffusion-weighted MRI data defining human NR, as well as resting state and task functional MRI data consistent with its functional role. First, a region corresponding to NR was derived from anatomical connectivity between HC and mPFC via diffusion-weighted imaging (Human Connectome Project data). Second, applying this NR mask as a seed in resting state functional connectivity analyses revealed robust correlations with mPFC and HC across ~1000 individuals (Human Connectome Project), another set of 17 individuals (experimenter-collected), and 88 scans of the same individual (MyConnectome). Finally, in an experimenter-collected dataset of 17 individuals performing a memory task, we found evidence for NR mediating correlations between mPFC and HC. Together, these findings convey strong evidence for NR in the human brain, which may be critical to network interactions between mPFC and HC and memory-guided behavior.
Topic Area: LONG-TERM MEMORY: Other