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The object recognition task (ORT) is a popular one-trial learning test for animals. In the current study, we investigated several methodological issues concerning the task. Data was pooled from 28 ORT studies, containing 731 male Wistar rats. We investigated the relationship between 3 common absolute- and relative discrimination measures, as well as their(More)
The object recognition task is a commonly used test for the assessment of memory functions in rodents. In this paper different aspects concerning the analysis of object recognition data are discussed. Using a set of experimental studies and fictive data sets, it was shown that the absolute discrimination measure (d1) behaves different from the ratio(More)
The object recognition task (ORT) allows assessing learning and memory processes in rodents. In this study, two areas in which knowledge about the ORT could be extended were addressed; i.e. generality to species and strains, and intervening variables including housing and estrous cycle. Regarding generality to species and strains, the ORT performance of(More)
A promising target for memory improvement is phosphodiesterase type 5 (PDE5), which selectively hydrolyzes cyclic guanosine monophosphate (cGMP). In rodents, PDE5 inhibitors (PDE5-Is) have been shown to improve memory performance in many behavioral paradigms. However, it is questioned whether the positive effects in animal studies result from PDE5(More)
The 5-hydroxytryptamine(6) (5-HT(6)) receptor has been suggested to play an important role in the regulation of memory and cognition. In the present study, our aim was to investigate whether the novel, selective 5-HT(6) antagonists compound (CMP) X and CMP Y and the reference 5-HT(6) antagonist GSK-742457 could ameliorate impairments in episodic memory in(More)
The second messengers cGMP and cAMP have a vital role in synaptic plasticity and memory processes. As such, phosphodiesterases inhibitors (PDE-Is), which prevent the breakdown of these cyclic nucleotides, represent a potential treatment strategy in memory decline. Recently it has been demonstrated that cGMP and cAMP signaling act in sequence during memory(More)
In previous studies, we have shown that phosphodiesterase type 5 inhibitors (PDE5-Is) can improve early consolidation of object memory. These conclusions were based on the timing of drug administration relative to the learning trial (i.e. before or after). However, there are very little pharmacological data available about the pharmacokinetic profile of(More)
Drug effects are usually evaluated in animals housed under maximally standardized conditions. However, it is assumed that an enriched environment (EE) more closely resembles human conditions as compared to maximally standardized laboratory conditions. In the present study, we examined the acute cognition enhancing effects of vardenafil, a PDE5 inhibitor,(More)
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(More)
In previous studies, we have shown that acetylcholinesterase inhibitors and phosphodiesterase inhibitors (PDE-Is) are able to improve object memory by enhancing acquisition processes. On the other hand, only PDE-Is improve consolidation processes. Here we show that the cholinesterase inhibitor donepezil also improves memory performance when administered(More)