[Abstract Title]. - Society for Neuroscience

Authors: *D. A. MACQUEEN 1 , L. A. BULLARD 2 , T. GUZE 2 , M. GALIZIO 2 ;
2 Psychology, 1 UNCW, Wilmington, NC
Abstract: The lack of procedures suitable to assess working memory capacity in non-humans
has limited neurobiological research in this area. The olfactory memory span procedure (OMS)
recently developed by Dudchenko, Wood & Eichenbaum (2000), appears a promising candidate
to study working memory capacity in rodents. The present study sought to evaluate a variation of
the OMS and used it to investigate the effects of the non-competitive NMDAr antagonist,
dizocilpine, and the opioid agonist, morphine in rats. The OMS task was designed as an animal
analogue to the human digit span task. Rats were placed in a large arena with 18 food locations.
In the initial trial of each session, one food cup marked with a distinct olfactory stimulus was
present and responding to it was reinforced. Each subsequent trial added a new olfactory
stimulus and responding to the new stimulus was always reinforced (non-matching). The
dependent measures were number of stimuli that incremented without error (span) and overall
percent correct responses. Sessions were conducted five days per week and each session included
24 trials of the OMS task as well as a performance control task involving a simple olfactory
discrimination. Five male Sprague-Dawley rats received 30 or more sessions of training on the
OMS task and drug administration began when performances met criteria for accuracy and
consistency over sessions. When the drug studies began, rats were exposed to i.p. injections prior
to the testing session twice per week with testing conducted under baseline conditions the other
three days. Dose effect functions were determined for morphine (saline, 1.0, 3.0, 5.6, 10.0 and
17.0 mg/kg) and dizocilpine (saline, .03, .10, .17, and .30 mg/kg). Baseline performance was
characterized by mean spans (M=8.7) that were similar to those reported by Dudchenko et al. and
decreasing percent correct as a function of memory set size. Both drugs produced significant
impairments on memory span and overall accuracy at the highest doses, but in the case of
morphine, these effects occurred only at high doses that also disrupted the performance control.
In contrast, dizocilpine produced significant impairments on the OMS task at doses (.10 and .17
mg/kg) that did not impair performance of the control. Thus, the effects of this NMDAr
antagonist can be interpreted in terms of selective impairment of working memory capacity.
Disclosures: D.A. MacQueen , None; L.A. Bullard, None; T. Guze, None; M. Galizio, None.
Poster
291. Animal Cognition and Behavior: Learning and Memory: Pharmacology II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 291.19/SS2
Topic: F.02.j. Learning and memory: Pharmacology
Support: NARSAD Young Investigator Award