Fornix white matter microstructure differentially predicts false recollection rates in older and younger adults

Abstract

Healthy aging is accompanied by increased false remembering in addition to reduced successful remembering in older adults. Neuroimaging studies implicate age-related differences in the involvement of medial temporal lobe and fronto-parietal regions in mediating highly confident false recollection. However, no studies have directly examined the relationship between white matter microstructure and false recollection in younger and older adults. Using diffusion-weighted imaging and probabilistic tractography, we examined how white matter microstructure within tracts connecting the hippocampus and the fronto-parietal retrieval network contribute to false recollection rates in healthy younger and older adults. We found only white matter microstructure within the fornix contributed to false recollection rates, and this relationship was specific to older adults. Fornix white matter microstructure did not contribute to true recollection rate, nor did common white matter contribute to false recollection, suggesting fornix microstructure is explicitly associated with highly confident false memories in our sample of older adults. These findings underlie the importance of examining microstructural correlates associated with false recollection in younger and older adults.

Keywords: Diffusion weighted imaging; False memory; Older adults.

Figure 1.

Tracts of interest. Group-average probabilistic maps of tracts of interest are depicted on the MNI T1 1mm template: fornix (yellow), forceps minor (pink), SLF (blue), ILF (red), dorsal cingulum bundle (green).

Figure 2.

Plots depicting the relationships between tract FA and false recollection. Age group moderated the relationship between fornix FA and recollection false alarms such that fornix FA negatively predicted recollection false alarms in older adults, but not younger adults.