Related Experiment Videos
Effect of excitotoxic lesions of rat medial prefrontal cortex on spatial memory
Laurent Lacroix1, Ilsun White, Joram Feldon
1Behavioural Neurobiology Laboratory, Swiss Federal Institute of Technology Zurich, Schorenstrasse 16, Postfach CH-8603, Schwerzenbach, Switzerland.
Abstract:
The involvement of medial prefrontal cortex (mPFC) in spatial learning was examined in two memory tasks using spatial components, the Morris water maze and the three-panel runway. Using the Morris water maze task, with an invisible platform, the effects of NMDA mPFC lesions were assessed in a procedure reflecting spatial learning and memory, including a spatial reversal. In the three-panel runway, a delayed matching-to-position procedure was used in which rats were required to find food at the end of the runway after passing through one of three panel gates set into four barriers spaced equally apart along the maze. In addition, mPFC lesions were assessed behaviorally in two behavioral tests known to be sensitive to mPFC dysfunction: the food hoarding paradigm and spontaneous locomotion in the open field. Consistent with the documented effects of mPFC damage, NMDA mPFC lesions impaired food hoarding behavior and increased spontaneous exploratory locomotion. In the Morris water maze and the three-panel runway, mPFC-lesioned rats showed relatively few effects, supporting the conclusion that the damage inflicted to the mPFC had no consequence for the processing of spatial information. However, mPFC lesioned animals showed slower acquisition during both the training trial in the three-panel runway and the reversal training in the Morris water maze. These results suggest that spatial memory did not depend on mPFC integrity in the Morris water maze and the three-panel runway experiments, and address the issue of deficits induced by mPFC lesions in memory tasks dependent on non-mnemonic processes such as attentional processes and/or a reduced behavioral flexibility to environmental changes.
Insights
The medial prefrontal cortex (mPFC) is not crucial for spatial memory in rats navigating mazes. However, mPFC lesions did impair learning acquisition and behavioral flexibility in these spatial tasks.
Area of Science:
- Neuroscience
- Cognitive Science
- Behavioral Neuroscience
Background:
- The medial prefrontal cortex (mPFC) plays a role in various cognitive functions.
- Its specific involvement in spatial learning and memory remains an area of investigation.
Purpose of the Study:
- To investigate the role of the medial prefrontal cortex (mPFC) in spatial learning and memory.
- To assess the impact of mPFC lesions on performance in the Morris water maze and a three-panel runway task.
Main Methods:
- NMDA-induced mPFC lesions were created in rats.
- Behavioral assessments included the Morris water maze, three-panel runway, food hoarding, and open field tests.
- Spatial learning, memory, and reversal learning were evaluated.
Main Results:
- mPFC lesions impaired food hoarding and increased spontaneous locomotion, consistent with known effects.
- Rats with mPFC lesions showed minimal deficits in the Morris water maze and three-panel runway tasks.
- However, mPFC-lesioned rats exhibited slower acquisition in the three-panel runway and slower reversal learning in the Morris water maze.
Conclusions:
- Spatial memory, in the context of these specific tasks, does not appear to depend on medial prefrontal cortex (mPFC) integrity.
- Deficits observed in mPFC-lesioned animals may relate to non-mnemonic processes like attention or behavioral flexibility rather than core spatial memory impairment.