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Research in the past has highlighted an inverse association between hippocampal and caudate volumes in younger and older adults (Bohbot et al., 2007; Sodums & Bohbot, 2020) with some additional evidence in Alzheimer’s disease (Persson et al., 2018). These observations were interpreted as indicative of competitive interactions between two spatial navigation/memory systems supported by these structures, with the hippocampus underlying place-learning and allocentric navigation (using world-referenced coordinates to navigate) and the caudate nucleus underlying response-learning which is similar to egocentric navigation (using self-reference coordinates to navigate; Ekstrom et al., 2014; Ekstrom et al., 2017; Packard & Mcgaugh, 1996). However, the previous studies analyzing such relationships were based on relatively small sample sizes, had limited investigation of the possibility of this competitive relationship existing with other brain regions, and did not incorporate longitudinal analyses. In addition, one study (Persson et al., 2018) suggested that there may be an initial increase in caudate volume in aging, as a compensatory mechanism for hippocampal atrophy, followed by caudate atrophy during the progression of Alzheimer’s disease (AD). Thus, our primary research goals are to a) determine whether we can replicate the inverse association between hippocampal and caudate volume in multiple samples across the lifespan and the AD spectrum; and b) determine whether the inverse association extends to other brain regions in the networks supporting the two navigation/memory systems again across the healthy lifespan and the AD spectrum; and c) examine longitudinal trajectories of the caudate nucleus, hippocampus and their ratio in older adults and across AD spectrum. Full details can be found in the attached preregistration document.

1Answers to Prayer, from George Müller's Narratives

By A. E. C. Brooks and George Müller

Mr. Brooks, in this compilation, has endeavored to select those incidents and practical remarks from Mr. Müller's Narratives, that show in an unmistakeable way, both to believers and unbelievers, the secret of believing prayer, the manifest hand of a living God, and His unfailing response, in His own time and way, to every petition which is according to His will. (From the Preface)