Multidomain cognitive assessment and high-resolution magnetic resonance imaging (MRI) across age in the male Fischer...

The mechanisms responsible for individual differences in cognition are not well understood. This study assessed behavioral performance and magnetic resonance imaging (MRI)-derived brain volumes in male Fischer 344 young (6 months), middle-aged (15 months), and aged (23 months) adult rats and asked two primary questions: Do individual differences in spatial performance predict behavior in other cognitive domains? Are the observed differences in cognition related to the volume of brain areas responsible for these cognitive processes? Several cognitive domains were examined here along with MRI-derived volumetric measures of the hippocampus and neocortex. The tasks assessed spatial reference and working memory, and temporal ordering and spatial location novelty tasks. The hippocampus-dependent spatial version of the Morris watermaze was used to categorize each rat into high, average, and low performers within each age group. When scores on the spatial working memory task were compared to the spatial reference memory task, only young adults showed a positive relationship between performance on these tasks; this relationship was not apparent in the older animals. With respect to MRI measurements, differences were found in total intracranial volume and total brain volume across age, but there were no statistically significant relationships found across age or between cognitive categories in the neocortex or hippocampus cornu ammonis subfields. Three primary conclusions can be drawn: There is large variability in spatial memory across all ages, high performance on one cognitive domain does not necessarily predict high performance on another, and finally, finer structural analyses may be required to identify brain changes responsible for the individual differences observed here. (PsycInfo Database Record (c) 2026 APA, all rights reserved).