Spatial memory extinction differentially affects dorsal and ventral hippocampal metabolic activity and associated functional brain networks.
Previous studies showed the involvement of brain regions associated with both spatial learning and associative learning in spatial memory extinction, although the specific role of the dorsal and ventral hippocampus and the extended hippocampal system including the mammillary body in the process is still controversial. The present study aimed to identify the involvement of the dorsal and ventral hippocampus, together with cortical regions, the amygdaloid nuclei, and the mammillary bodies in the extinction of a spatial memory task. To address these issues, quantitative cytochrome c oxidase histochemistry was applied as a metabolic brain mapping method. Rats were trained in a reference memory task using the Morris water maze, followed by an extinction procedure of the previously acquired memory task. Results show that rats learned successfully the spatial memory task as shown by the progressive decrease in measured latencies to reach the escape platform and the results obtained in the probe test. Spatial memory was subsequently extinguished as shown by the descending preference for the previously reinforced location. A control naïve group was added to ensure that brain metabolic changes were specifically related with performance in the spatial memory extinction task. Extinction of the original spatial learning task significantly modified the metabolic activity in the dorsal and ventral hippocampus, the amygdala and the mammillary bodies. Moreover, the ventral hippocampus, the lateral mammillary body and the retrosplenial cortex were differentially recruited in the spatial memory extinction task, as shown by group differences in brain metabolic networks. These findings provide new insights on the brain regions and functional brain networks underlying spatial memory, and specifically spatial memory extinction. © 2016 Wiley Periodicals, Inc.
['Méndez-Couz|Marta|M|', 'González-Pardo|Héctor|H|', 'Vallejo|Guillermo|G|', 'Arias|Jorge L|JL|', 'Conejo|Nélida M|NM|']
D000679:Amygdala D000818:Animals D002540:Cerebral Cortex D003576:Electron Transport Complex IV D005108:Extinction, Psychological D006624:Hippocampus D008297:Male D008326:Mammillary Bodies D018782:Maze Learning D009434:Neural Pathways D009483:Neuropsychological Tests D011897:Random Allocation D017208:Rats, Wistar D065852:Spatial Memory
spatial memory cytochrome c oxidase metabolic brain mapping rat mammillary bodies