Rhesus monkeys were conditioned to press on levers and receive intravenous infusions of cocaine or ketamine. Experimental conditions provided several different doses of drug during each of two daily 130 min sessions; as a result, a dose-response curve relating rate of responding to dose/injection for self-administered drug was obtained within each session. Relative rate-maintaining effects of n...

Hippocampal sharp wave-ripples (SPW-Rs) and associated place-cell reactivations are crucial for spatial memory consolidation during sleep and rest. However, it remains unclear how learning and consolidation requirements influence and regulate subsequent SPW-R activity. Indeed, SPW-R activity has been observed not only following complex behavioral tasks, but also after random foraging in familia...

BACKGROUND Several clinical reports have suggested that the mirtazapine-induced augmentation of risperidone activity may effectively improve treatment of the negative and certain cognitive symptoms of schizophrenia. METHODS The aim of the present study was to evaluate the effect of mirtazapine and risperidone, given separately or jointly, on the impact of MK-801(an NMDA receptor antagonist), ...

The role of glutamatergic N-methyl-D-aspartate (NMDA) receptors in memory storage processes was examined using systemic posttraining injections of MK-801. Male Long-Evans rats received an eight-trial (30-s ITI) training session on a spatial or cued water maze task. In the spatial task, a submerged escape platform was located in the same quadrant of the maze on all trials. In the cued task, a vi...

The objective of this study was to assess the effects of phosphodiesterase type 2 (PDE2) and type 10 (PDE10) inhibition on memory function in the object recognition task using the scopolamine- and MK-801-induced memory deficit model. The effects of the PDE2 inhibitor BAY 60-7550 and the PDE10 inhibitor PQ-10 on object recognition performance were investigated in the scopolamine (0.1mg/kg, i.p.)...

In this study, we evaluated the goldfish model of hemilabyrinthectomy for investigating potential recovery-promoting drugs. In this lesion model, the unilateral removal of the labyrinth induces a postural imbalance in response to light (Dorsal Light Reflex), from which the animals can recover over time. The behavioral effects of two neuropeptides were tested--namely, of substance P and ACTH4-10...

The NMDA receptor antagonist MK-801 produces different effects on timing tasks. In particular, MK-801 produces an underestimation of duration when animals are tested with the differential reinforcement of low rate of responding (DRL) schedule and an overestimation of duration when animals are tested with the peak-interval (PI) procedure. The goal of this study was to develop a model-based expla...

Six experiments studied the role of conditioned stimulus (CS) familiarity in determining the effects of the N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 on fear extinction. Systemic administration of MK-801 (0.1 mg/kg) impaired initial extinction but not reextinction learning. MK-801 impaired reextinction learning when the CS was relatively novel during reextinction training but not i...

The role of AMPA receptors (AMPARs) in generation and propagation of respiratory rhythm is well documented both in vivo and in vitro, whereas the functional significance of NMDA receptors (NMDARs) in preBötzinger complex (preBötC) neurons has not been explored. Here we examined the interactions between AMPARs and NMDARs during spontaneous respiratory rhythm generation in slices from neonatal ra...

The NMDA receptor opens in response to binding of NMDA and glycine. However, it remains unclear where and how gating of the NMDA receptor pore is accomplished. We show that different point mutations between S645 and I655 (thus including the highly conserved SYTANLAAF motif) of M3c in NR2B lead to constitutively open channels. The current through these constitutively open channels are readily bl...