Parallel modifications of spatial memory performances, exploration patterns, and hippocampal theta rhythms in fornix-damaged rats: reversal by oxotremorine.
Learning scores and degrees of divergence of the exploratory patterns (EP) displayed during the acquisition stage of a radial eight-arm maze task were examined in fornix-damaged and sham-operated rats injected either with oxotremorine (0.1 mg/kg) or saline. Modifications of hippocampal rhythmic slow activity (theta) recorded in each condition were analyzed in CA1 and dentate gyrus. Dorsal fornix sections reduced choice accuracy but also induced the adoption of weakly divergent EP. Oxotremorine in animals with lesions reinstates both learning scores and degree of divergence of EP at the levels respectively observed in saline sham-operated animals. Finally, oxotremorine in sham-operated animals did not significantly improve choice accuracy but strongly modified the EP. Preoperatively, theta rhythms indicated a decrease of frequency after oxotremorine administration. Postoperatively, they showed an increase of frequency in animals with lesions that were reinstated at the preoperative level by oxotremorine.
Maho
C
C
Département de Psychophysiologie, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
Dutrieux
G
G
Ammassari-Teule
M
M
D000818:Animals; D001143:Arousal / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects; D004569:Electroencephalography; D005106:Exploratory Behavior / Q000187:drug effects*; D006624:Hippocampus / Q000187:drug effects*; D008297:Male; D008568:Memory / Q000187:drug effects*; D011939:Mental Recall / Q000187:drug effects*; D009043:Motor Activity / Q000187:drug effects; D009434:Neural Pathways / Q000187:drug effects; D009949:Orientation / Q000187:drug effects; D010095:Oxotremorine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012686:Septal Nuclei / Q000187:drug effects*; D013028:Space Perception / Q000187:drug effects*; D013826:Theta Rhythm
D010095:Oxotremorine