Detecting drug effects on short-term memory function using a combined delayed matching and non-matching to position task.
Operant delayed non-matching-to-position (DNMTP) and delayed matching-to-position (DMTP) have become standard techniques to investigate drug effects on short-term memory function in rats. However, these two tasks are normally conducted in isolation. Using two standard drugs, the 5HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), and the muscarinic antagonist scopolamine, this study looked at a two-choice operant task that essentially involved a mixed DNMTP/DMTP paradigm. Thus, DNMTP trials were interspersed with DMTP trials in a random sequence for the duration of a session. 8-OH-DPAT (0.03 mg/kg) slightly but significantly improved response accuracy in a delay-dependent fashion during DMTP but not DNMTP trials. The highest dose of 8-OH-DPAT (0.1 mg/kg) impaired accuracy during DNMTP trials independent of delay and had no significant effect during DMTP trials. Scopolamine (0.1 mg/kg) produced delay-dependent deficits in accuracy during DMTP trials but delay-independent impairments during DNMTP trials. Because both 8-OH-DPAT and scopolamine produced delay-dependent effects with DMTP trials types and either had no effect (8-OH-DPAT) or produced delay-independent impairments (scopolamine) during DNMTP trials types, it is suggested that DMTP trials had a greater dependence on short-term working memory function than DNMTP trials that probably relied more on positional (mediating) strategies for solving the task. Therefore, we believe that this mixed DNMTP/DMTP task offers greater potential for more reliable and discerning interpretation of data regarding short-term memory function in rodents than either of the paradigms performed in isolation.
Pache
D M
DM
Mechanisms of Drug Action Group, Welsh School of Pharmacy, Cardiff University, Cathays Park, United Kingdom. PacheD@cardiff.ac.uk
Sewell
R D
RD
Spencer
P S
PS
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced; D008570:Memory, Short-Term / Q000187:drug effects*; D018727:Muscarinic Antagonists / Q000494:pharmacology; D011581:Psychological Tests; D051381:Rats; D017208:Rats, Wistar; D012601:Scopolamine / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013997:Time Factors
D018727:Muscarinic Antagonists; D017366:Serotonin Receptor Agonists; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D012601:Scopolamine