title: Virtual navigation strategies from childhood to senescence: evidence for changes across the life span.
abstract: This study sought to investigate navigational strategies across the life span, by testing 8-years old children to 80-years old healthy older adults on the 4 on 8 virtual maze (4/8VM). The 4/8VM was previously developed to assess spontaneous navigational strategies, i.e., hippocampal-dependent spatial strategies (navigation by memorizing relationships between landmarks) versus caudate nucleus-dependent response strategies (memorizing a series of left and right turns from a given starting position). With the 4/8VM, we previously demonstrated greater fMRI activity and gray matter in the hippocampus of spatial learners relative to response learners. A sample of 599 healthy participants was tested in the current study. Results showed that 84.4% of children, 46.3% of young adults, and 39.3% of older adults spontaneously used spatial strategies (p < 0.0001). Our results suggest that while children predominantly use spatial strategies, the proportion of participants using spatial strategies decreases across the life span, in favor of response strategies. Factors promoting response strategies include repetition, reward and stress. Since response strategies can result from successful repetition of a behavioral pattern, we propose that the increase in response strategies is a biological adaptive mechanism that allows for the automatization of behavior such as walking in order to free up hippocampal-dependent resources. However, the down-side of this shift from spatial to response strategies occurs if people stop building novel relationships, which occurs with repetition and routine, and thereby stop stimulating their hippocampus. Reduced fMRI activity and gray matter in the hippocampus were shown to correlate with cognitive deficits in normal aging. Therefore, these results have important implications regarding factors involved in healthy and successful aging.
authors.affiliation: Department of Psychiatry, Douglas Institute, McGill University Verdun, QC, Canada.
authors.forename: Veronique D
authors.initials: VD
authors.lastname: Bohbot
authors.forename: Sam
authors.initials: S
authors.lastname: McKenzie
authors.forename: Kyoko
authors.initials: K
authors.lastname: Konishi
authors.forename: Celine
authors.initials: C
authors.lastname: Fouquet
authors.forename: Vanessa
authors.initials: V
authors.lastname: Kurdi
authors.forename: Russel
authors.initials: R
authors.lastname: Schachar
authors.forename: Michel
authors.initials: M
authors.lastname: Boivin
authors.forename: Philippe
authors.initials: P
authors.lastname: Robaey