Dataset Information

The hippocampus and spatial memory: findings with a novel modification of the water maze.

ABSTRACT: For many tasks and species, remote memory (but not recent memory) is spared after damage to the hippocampus. An exception to this pattern of findings has been that both recent and remote memory are impaired after hippocampal lesions when rats are trained in the conventional water maze task. We explored the effect of introducing a navigational beacon for rats to use during testing. Four identical beacons were hung directly over each of the water maze quadrants, equidistant from each other (multiple-beacon maze). One of the beacons was always directly over the hidden platform. By using distal spatial cues, rats could select the correct beacon and use that beacon as a guide to the hidden platform. Probe tests indicated that rats did use the beacons to guide performance throughout training. Two months after the completion of training, rats were given hippocampal or sham lesions. Controls performed well, but the lesion group performed at chance on the retention probe trials. Furthermore, the rats with lesions not only searched indiscriminately in all four quadrants, they also did not use the beacons. These results indicate that impaired performance in the water maze after hippocampal damage reflects more than a loss of spatial information.

SUBMITTER: Clark RE

PROVIDER: S-EPMC2553679 | biostudies-literature | 2007 Jun

REPOSITORIES: biostudies-literature

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The hippocampus and spatial memory: findings with a novel modification of the water maze.

Clark Robert E RE Broadbent Nicola J NJ Squire Larry R LR

The Journal of neuroscience : the official journal of the Society for Neuroscience 20070601 25

For many tasks and species, remote memory (but not recent memory) is spared after damage to the hippocampus. An exception to this pattern of findings has been that both recent and remote memory are impaired after hippocampal lesions when rats are trained in the conventional water maze task. We explored the effect of introducing a navigational beacon for rats to use during testing. Four identical beacons were hung directly over each of the water maze quadrants, equidistant from each other (multip ...[more]

PMID: 17581951

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Project description:Explicit and implicit learning and memory networks exist where each network can facilitate or inhibit cognition. Clinical evidence suggests that implicit networks are relatively preserved after traumatic brain injury (TBI). Non-spatial pre-training (NSPT) in the Morris Water Maze (MWM) provides the necessary behavioral components to complete the task, while limiting the formation of spatial maps. Our study utilized NSPT in the MWM to assess implicit and explicit learning and memory system deficits in the controlled cortical impact (CCI) model of TBI. 76 adult male Sprague-Dawley rats were divided: CCI vs. sham surgery, NSPT vs. No-NSPT, and cued vs. non-cued groups. NSPT occurred for 4d prior to surgery (dynamic hidden platform location, extra-maze cues covered, static pool entry point). Acquisition (d14-18), Probe/Visible Platform (d19), and Reversal (d20-21) trials were conducted with or without extra-maze cues. Novel time allocation and search strategy selection metrics were utilized. Results indicated implicit and explicit learning/memory networks are distinguishable in the MWM. In the cued condition, NSPT reduced thigmotaxis, improved place learning, and largely eliminated the apparent injury-induced deficits typically observed between untrained CCI and sham rats. However, among NSPT groups, incorporation of cues into search strategy selection for CCI rats was relatively impaired compared to shams. Non-cued condition performance showed sham/NSPT and CCI/NSPT rats perform similarly, suggesting implicit memory networks are largely intact 2weeks after CCI. Place learning differences between CCI/NSPT and sham/NSPT rats more accurately reflect spatial deficits in our CCI model compared to untrained controls. These data suggest NSPT as a clinically relevant construct for evaluating potential neurorestorative and neuroprotective therapies. These findings also support development of non-spatial cognitive training paradigms for evaluating rehabilitation relevant combination therapies.

Dataset Information

The hippocampus and spatial memory: findings with a novel modification of the water maze.

Publications

The hippocampus and spatial memory: findings with a novel modification of the water maze.

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