Retrograde amnesia for spatial information: a dissociation between intra and extramaze cues following hippocampus lesions in rats.
Several recent studies have shown a flat retrograde amnesia for spatial information following lesions to the hippocampus in rats and mice. However, the results of the present investigation demonstrate that in rats that presurgically learned a spatial reference memory task based on extramaze cues, a temporally graded retrograde amnesia is evident following lesions to the hippocampus (1, 16, 32 or 64 days after learning) if two conditions are met. First, that a wide range of retention intervals is used, and second, that independent groups of rats are tested, not a single group that learns different spatial discrimination tasks at different times (expt 1). The results of expt 2 show that the hippocampus does not serve as a consolidating mechanism when the spatial task learned presurgically is based on intramaze cues. Taken together, these results indicate that the hippocampus is critical for the storage and/or retrieval of spatial reference information that was learned up to 1 month before hippocampus damage; however, in the absence of the hippocampus, efficient retention can still occur provided that the spatial knowledge was learned in a simple associative manner.
Ramos
J M
JM
Departamento de Psicología Experimental y Fisiología del Comportamiento, Facultad de Psicología, Instituto de Neurociencias, F. Oloriz, Universidad de Granada, Spain. jmjramos@platon.ugr.es
D000648:Amnesia, Retrograde / Q000503:physiopathology*; D000818:Animals; D003463:Cues; D006624:Hippocampus / Q000293:injuries* / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008568:Memory / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013028:Space Perception / Q000502:physiology*; D013997:Time Factors