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Hippocampal lesions produce both nongraded and temporally graded retrograde amnesia in the same rat

Authors

  • Gordon Winocur,

    Corresponding author
    1. Rotman Research Institute, Baycrest Centre, Toronto, Canada
    2. Department of Psychology, Trent University, Peterborough, Canada
    3. Department of Psychology, University of Toronto, Toronto, Canada
    4. Department of Psychiatry, University of Toronto, Toronto, Canada
    • Rotman Research Institute, Baycrest Centre, 3560 Bathurst Street, Toronto, Ontario, Canada M6A 2E1
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  • Melanie J. Sekeres,

    1. Rotman Research Institute, Baycrest Centre, Toronto, Canada
    2. Department of Physiology, University of Toronto, Toronto, Canada
    3. Programs in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada
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  • Malcolm A. Binns,

    1. Rotman Research Institute, Baycrest Centre, Toronto, Canada
    2. Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
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  • Morris Moscovitch

    1. Rotman Research Institute, Baycrest Centre, Toronto, Canada
    2. Department of Psychology, University of Toronto, Toronto, Canada
    3. Department of Psychology, Baycrest Centre, Toronto, Canada
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Abstract

Rats were administered contextual fear conditioning and trained on a water-maze, spatial memory task 28 days or 24 h before undergoing hippocampal lesion or control surgery. When tested postoperatively on both tasks, rats with hippocampal lesions exhibited retrograde amnesia for spatial memory at both delays but temporally graded retrograde amnesia for the contextual fear response. In demonstrating both types of retrograde amnesia in the same animals, the results parallel similar observations in human amnesics with hippocampal damage and provide compelling evidence that the nature of the task and the type of information being accessed are crucial factors in determining the pattern of retrograde memory loss associated with hippocampal damage. The results are interpreted as consistent with our transformation hypothesis (Winocur et al. (2010a) Neuropsychologia 48:2339–2356; Winocur and Moscovitch (2011) J Int Neuropsychol Soc 17:766–780) and at variance with standard consolidation theory and other theoretical models of memory. © 2013 Wiley Periodicals, Inc.

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