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Published on: June 26, 2013
Mind the gap: delayed manifestation of long-term object memory improvement by phosphodiesterase inhibitors
S Akkerman1, A Blokland2, J Prickaerts1
1Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (EURON), Maastricht, The Netherlands.
Abstract:
We examined the temporal profile of pharmacologically enhanced episodic memory, using the object recognition task. Male Wistar rats were tested at different retention intervals ranging from 1 h to 24 h. The object discrimination performance of all groups (untreated, placebo, drug treatment) gradually decreased up to an interval (8 h). Interestingly, only after this 8 h interval the memory improving effects of vardenafil and rolipram started to emerge. This time-dependent memory performance shows similarities with the Kamin effect. The delayed manifestation of drug-enhanced memory suggests that two separate memory mechanisms are at play, a quick transient form of memory and a more stable memory form that requires several hours to develop. It is important to take this into account when testing treatments intended for long-term memory enhancement.
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