Nonredundant roles for hippocampal and entorhinal cortical plasticity in spatial memory storage.
Recently, it has been demonstrated that targeted blockade of the extracellular signal-regulated kinase (ERK) cascade in either the entorhinal cortex (EC) or hippocampus (HIP) results in spatial memory deficits. However, it is unclear if ERK-mediated plasticity in these structures has redundant functions or unique roles. In this report, we contrast the role of long-term plasticity in these two structures with side-by-side comparisons of the effects of PD098059 infusion following water maze training. Analysis of performance during the long-term retention test indicates a role for plasticity in the EC in storing broad location information. In contrast, blocking plasticity in the HIP resulted in deficits in indices of precise location information and goal-directed navigational error. To distinguish between a navigational and location deficit, a "two-room" experimental design was employed. Training in the first room allowed animals to consolidate information regarding navigational strategies prior to training and drug infusion in the second room. Hippocampal-PD098059-infused animals demonstrated behavior suggestive of an expanded representation of the platform location and, thus, a loss of precise location information, suggesting that plasticity in these structures is involved in nonredundant, but complementary, processes necessary for spatial memory.
Hebert
April E
AE
The Vivian L. Smith Center for Neurologic Research, Department of Neurobiology and Anatomy, The University of Texas Medical School, P.O. Box 20708, Houston, TX 77225, USA.
Dash
Pramod K
PK
D000818:Animals; D002404:Catheterization; D004305:Dose-Response Relationship, Drug; D018728:Entorhinal Cortex / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D005419:Flavonoids / Q000008:administration & dosage / Q000494:pharmacology; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009949:Orientation / Q000187:drug effects; D051381:Rats; D020318:Rats, Long-Evans; D013028:Space Perception / Q000502:physiology*
D004791:Enzyme Inhibitors; D005419:Flavonoids; D048049:Extracellular Signal-Regulated MAP Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one