Does hippocampal volume explain performance differences on hippocampal-dependent tasks?

Abstract

46Marked disparities exist across healthy individuals in their ability to imagine scenes, recall 47 autobiographical memories, think about the future and navigate in the world. The importance 48 of the hippocampus in supporting these critical cognitive functions has prompted the question 49 of whether differences in hippocampal grey matter volume could be one source of performance 50 variability. Evidence to date has been somewhat mixed. In this study we sought to mitigate 51 issues that commonly affect these types of studies. Data were collected from a large sample of 52 217 young, healthy adult participants, including whole brain structural MRI data (0.8mm 53 isotropic voxels) and widely-varying performance on scene imagination, autobiographical 54 memory, future thinking and navigation tasks. We found little evidence that hippocampal grey 55 matter volume was related to task performance in this healthy sample. This was the case using 56 different analysis methods (voxel-based morphometry, partial correlations), when whole brain 57 or hippocampal regions of interest were examined, when comparing different sub-groups 58 (divided by gender, task performance, self-reported ability), and when using latent variables 59 derived from across the cognitive tasks. Hippocampal grey matter volume may not, therefore, 60 significantly influence performance on tasks known to require the hippocampus in healthy 61 people. Perhaps only in extreme situations, as in the case of licensed London taxi drivers, are 62 measurable ability-related hippocampus volume changes consistently exhibited. 63 64 65 KEYWORDS 66 Hippocampal volume; scene construction; autobiographical memory; future thinking; spatial 67 navigation; individual differences 68 69 A larger number of studies have investigated the relationship between hippocampal 103 volume and memory ability in healthy individuals, but with mixed results. On the one hand, 104

The relationship between hippocampal-dependent task performance and hippocampal grey matter myelination and iron content

“…All tasks are published and were performed and scored as per their published use. Full descriptions are also provided in Clark et al (2019, 2020) and Clark and Maguire (2020). Details of the double scoring for this study are provided in the Supplemental Material Tables S1–S4.…”

“…Age, gender, total intracranial volume and MRI scanner were included as covariates in all analyses, with the exception of those examining gender, where gender was not a covariate. As in Clark et al (2020), statistical correction was made using false discovery rate (FDR; Benjamini and Hochberg, 1995), with an FDR of p < 0.05 allowing for 5% false-positive results across the tests performed and calculated using the resources provided by McDonald (2014).…”

“…We used the large data set (n = 217) from Clark et al’s (2020) study that comprised an MPM quantitative imaging protocol (Callaghan et al, 2015, 2019; Weiskopf et al, 2013), and cognitive task performance with wide variability in scores. While aspects of these data (hippocampal grey matter volume, cognitive task performance) have been reported before (Clark et al, 2019, 2020; Clark and Maguire, 2020), the tissue microstructure MRI data, measuring myelination and iron content, have not been published previously. The mixed literature relating to hippocampal grey matter volume and the dearth of studies investigating hippocampal grey matter myelination and iron content made the formulation of clear hypotheses difficult.…”

The relationship between hippocampal subfield volumes and autobiographical memory persistence

“…By contrast, in real‐world contexts, the hippocampus is involved in the retrieval of multi‐faceted, multi‐modal autobiographical memories of our personal past experiences (Steinvorth, Levine, & Corkin, 2005). However, even when autobiographical memory recall was examined in a wide‐ranging analysis of healthy people, Clark, Monk, Hotchin, et al (2020) did not find any significant relationship between overall hippocampal volume and recall of internal (episodic) details, a widely‐used measure from the Autobiographical Interview (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002). To the best of our knowledge, only one study has examined the links between hippocampal subregion volumes and autobiographical memory recall in healthy individuals, reporting a positive association between the number of internal details on the Autobiographical Interview (Levine et al, 2002) and the volume of both the left subiculum and the combined left dentate gyrus (DG)/CA2/CA3 region (Palombo et al, 2018).…”

“…Neurosurgical resection (Scoville & Milner, 1957), as well as encephalitic (Miller et al, 2017, 2020), neurodegenerative (Petersen et al, 2000; Zhao et al, 2019), epileptic (Reminger et al, 2004), and psychiatric (Herold et al, 2013; Vythilingam et al, 2004) pathologies lead to reductions in hippocampal volume with concomitant memory impairments. However, the evidence for an association between hippocampal volume and episodic memory in healthy individuals is mixed (Van Petten, 2004; see Clark et al, 2020 for a recent full discussion). Some of these inconsistencies may be driven by the complex developmental trajectory of hippocampal structure (Tamnes, Bos, van de Kamp, Peters, & Crone, 2018), and ageing‐related atrophy (Gorbach et al, 2017; Langnes et al, 2020; Nordin, Herlitz, Larsson, & Söderlund, 2017).…”