title: Can rats control previously acquired spatial information? Evidence of "directed forgetting" phenomenon in delay-interposed radial maze behavior.
abstract: "Directed forgetting" is a method and a phenomenon used to investigate whether organisms can control memory with instructions to forget, and to remember. We examined directed forgetting phenomenon in rats, using a modified radial maze task. In the delay-interposed radial maze task, a 120-min delay followed four correct choices, during which rats were placed in either a white or black box, that signaled whether a second-half performance will be required (remember (R)-trial), or not (forget (F)-trial) after the delay. R- and F-trials were repeated 5 times each, followed by a "probe test," in which the second-half performance was conducted, although the F-cue was presented during the delay period. Rats made more errors in the probe test than in the R-trial. These results demonstrate the "directed forgetting" phenomenon in a radial maze task in rats, and suggest that rats can indeed control previously acquired spatial information, even situations with a long retention interval interposed. Although the mechanism by which presentation of the "forget-cue" influences rats' information processing remains unclear, several brain regions, including the medial prefrontal cortex and the hippocampal CA3 area, were shown to be more activated in the "remember"-cued trial than in the "forget"-cued trial, suggesting that these areas are potentially related to the "directed forgetting" phenomenon of spatial information demonstrated in the study.
authors.affiliation: Institute of Psychology and Behavioral Neuroscience, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Kaku
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamada
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ichitani
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002755:Choice Behavior / Q000502:physiology*; D003463:Cues; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar