It is well established that the NMDA receptor antagonists block hippocampal long-term potentiation and impair acquisition in the Morris watermaze task, although the role of individual NMDA receptor subtypes is largely unknown. In the present study, we compared the effects of (+/-)-CP-101,606, an antagonist selective for NMDA receptor NR1/NR2B subunit-containing receptors and the nonselective NM...

This paper presents a new algorithm for goalindependent Q-learning. The model was tested on a simulation of the Morris watermaze task. The new model learns faster than conventional Q-learning and experiences no interference when the goal location is moved. Once the new location is discovered the system is able to navigate directly to the platform on subsequent trials. The model was also tested ...

Spatial learning of transgenic mice is often assessed in the Morris watermaze, where mice must use distant cues to locate a submerged platform. Such learning is confounded by species-specific noncognitive swimming strategies. Factor analysis permits cognitive and noncognitive strategies to be disentangled and their association with electrophysiological phenomena to be investigated.

In rodent stroke models, investigation of deficits in spatial memory using the Morris watermaze may be confounded by coexisting sensory or motor impairments. To target memory specifically, we devised a watermaze protocol to minimize the impact of sensory and motor impairments in female Lister-hooded rats exposed to proximal electrocoagulation of the middle cerebral artery (MCAO). Rats were trai...

Prior experience has been shown to improve learning in both humans and animals, but it is unclear what aspects of recent experience are necessary to produce beneficial effects. Here, we examined the capacity of rats with complete hippocampal lesions, restricted CA1 lesions, or sham surgeries to benefit from prior experience. Animals were tested in two different spatial tasks in the watermaze, t...

Changes of synaptic connections between neurons are thought to be the physiological basis of learning. These changes can be gated by neuromodulators that encode the presence of reward. We study a family of reward-modulated synaptic learning rules for spiking neurons on a learning task in continuous space inspired by the Morris Water maze. The synaptic update rule modifies the release probabilit...

The dorsal hippocampus is crucial for learning the hidden-platform location in the hippocampus-dependent, spatial watermaze task. We have previously demonstrated that the postburst afterhyperpolarization (AHP) of hippocampal pyramidal neurons is reduced after acquisition of the hippocampus-dependent, temporal trace eyeblink conditioning task. We report here that the AHP and one or more of its a...

Hippocampal lesions often produce temporally graded retrograde amnesia (TGRA), whereby recent memory is impaired more than remote memory. This finding has provided support for the process of systems consolidation. However, temporally graded memory impairment has not been observed with the watermaze task, and the findings have been inconsistent with context fear conditioning. One possibility is ...

Rats with lesions in the perirhinal cortex and their control group learnt to discriminate between mirror-imaged visual landmarks to find a submerged platform in a watermaze. Rats initially learnt this discrimination passively, in that they were repeatedly placed on the platform in one corner of a square watermaze with walls of different appearance, prior to swimming to that same location for th...