Emergence of a Cue Strategy Preference on the Water Maze Task in Aged C57B6 × SJL F1 Hybrid Mice

  1. Michelle M. Nicolle1,3,4,
  2. Sonya Prescott1, and
  3. Jennifer L. Bizon2,3
  1. 1Department of Molecular Neuroscience, Mayo Graduate School, Mayo Clinic, Jacksonville, Florida 32224, USA
  2. 2Department of Psychology, Texas A&M University, College Station, Texas 77843-4235, USA

Abstract

The effects of age on cue learning, spatial reference memory, and strategy preference were assessed in B6 × SJL F1 mice by using the Morris water maze. This mouse strain is of particular interest because it is the background strain for a common transgenic model of Alzheimer's disease, the Tg2576 mouse, which develops plaques and other neurobiological markers of pathology beginning at 8 mo and increasing in severity with advanced age. In the current study, 12- and 23-mo-old C57B6 × SJL F1 mice were serially trained in cue and place versions of the Morris water maze task. At the completion of training, mice received a strategy probe test in which place (hidden) and cue (visible) strategies were in competition. Cue and spatial learning ability was maintained between 12 and 23 mo of age; however, on the strategy preference probe test, the 23-mo-old mice exhibited a significant bias toward the selection of a cue strategy. There was no relationship between strategy preference in the probe test and spatial learning ability, but the 23-mo-old mice did exhibit a strong trend toward shorter latencies during visible platform training, possibly reflecting the enhanced function of striatal-based neural systems in aging. These data demonstrate that 23-mo-old C57B6 × SJL F1 mice are capable of effective place learning, but if a place strategy is pitted against the use of a cue strategy, the use of a cue strategy predominates in the aged mice. The strategy preference observed here may reflect an emergence of differential processing in underlying brain circuitry with age in the B6 × SJL F1 mouse strain.

Footnotes

  • Article and publication are at http://www.learnmem.org/cgi/doi/10.1101/lm.64803.

  • 3 These authors contributed equally to this work.

    • Accepted September 25, 2003.
    • Received June 18, 2003.
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