Calorie Restriction and Working Memory

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Calorie Restriction and Working Memory

• Susanne Stahl-Bell,
• Tammy L. Cruz, David Young,
• and
• Mark S. Schmidt
• Columbus State University
• Stahl-Bell, S., Cruz, T.L., Young, D., Schmidt,
  M.S. (2002, April). Calorie restriction and
  working memory. Poster presented at the 1st
  Annual Georgia Undergraduate Research in
  Psychology Conference, Kennesaw State University,
  Kennesaw, GA.

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Introduction

• Calorie restriction (CR) is known to slow several
  aspects of biological aging and to extend the
  life-span 2,4,5,8,12,13.
• CRs potential for slowing the deficits
  associated with cognitive aging has not been
  extensively studied. The few studies which have
  been done with animals have used maze tasks and
  produced mixed results 1,3,6,7,9,11.
• The present pilot project is designed to test the
  effects of long-term calorie restriction on
  working memory in old rats using an automated,
  delayed-alternation procedure similar to those
  used in drug research with old rats 10.

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Subjects

• Twelve male rats of the F344xBN strain were
  acquired from Harlan Sprague Dawley.
• Four young (3 months-old) ad lib (AL) fed rats
• Four old (18 months-old) AL fed rats
• Four old (18 months-old) calorie restricted (CR)
  rats
• CR was initiated at 14 weeks of age at 10
  restriction, increased to 25 at 15 weeks, and to
  40 at 16 weeks where it was maintained.

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Procedure

• A Delayed Alternation Task in a Skinner-Box was
  used to test working memory.
• The rat has to learn to alternate between left
  and right on each trial.
• Rats can learn this task to a high level of
  accuracy.
• It requires the rat to remember where he went on
  the last trial (working memory).

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Procedure
However, the task becomes much harder when delays
are inserted between the trials.
Accuracy
Short Long
Delay
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Hypothesis
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Preliminary Results

• Calorie restriction significantly lowered body
  weight in the CR rats compared to the old AL and
  young AL rats, F (2,9) 163, p lt .001 (see
  Figure 1).
• All four of the young AL rats, three of the old
  AL rats, and three of the old CR rats have
  learned the alternation task after 4 months of
  training.
• The old AL rats required fewer training trials
  than both the young AL and old CR rats, but this
  difference was not statistically significant (see
  Figure 2).
• Working memory has been tested in all four of the
  young AL rats and two of the old AL rats with
  delays of 030 seconds. Accuracy decreased in
  both groups as a function of delay, but there
  were no statistically significant differences
  (see Figure 3).

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Discussion

• Our hypothesis that calorie-restriction will
  lessen the working memory deficits observed in
  old rats has not been supported so far in this
  pilot study.
• On the contrary, the old AL rats learned the
  alternation task faster than both the old CR rats
  and the young AL rats and no differences have
  been found in working memory when the rats were
  tested with delays.
• We believe that the high drive state (hunger) in
  the old CR rats might be interfering with their
  ability to learn the task.
• Data collection will continue until all rats have
  been tested with delays to allow for a better
  between-group comparison.

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References

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