The perirhinal cortex of the rat is necessary for spatial memory retention long after but not soon after learning

Departamento de Psicología Experimental y Fisiología del Comportamiento, Facultad de Psicología, Universidad de Granada, Campus de Cartuja, Spain.
Physiology & Behavior (Impact Factor: 2.98). 10/2005; 86(1-2):118-27. DOI: 10.1016/j.physbeh.2005.07.004
Source: PubMed


Many observations in humans and experimental animals support the view that the hippocampus is critical immediately after learning in order for long-term memory formation to take place. However, exactly when the medial temporal cortices adjacent to the hippocampus are necessary for this process to occur normally is not yet well known. Using a spatial task, we studied whether the perirhinal cortex of rats is necessary to establish representations in long-term memory. Results showed that, in a spatial task sensitive to hippocampal lesions, control and perirhinal lesioned rats can both learn at the same rate (Experiment 1). Interestingly, a differential involvement of the perirhinal cortex in memory retention was observed as time passes after learning. Thus, 24 days following the end of learning, lesioned and control rats remembered the task perfectly as measured by a retraining test. In contrast, 74 days after the learning the perirhinal animals showed a profound impairment in the retention of the spatial information (Experiment 2). Taken together, these results suggest that the perirhinal region is critical for the formation of long-term spatial memory. However, its contribution to memory formation and retention is time-dependent, it being necessary only long after learning takes place and not during the phase immediately following acquisition.

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    • "Although abundant studies shows the hippocampus is crucial for memory acquisition and recalling, it is still in controversy whether the hippocampus is critical for familiarity recognition or not [27]. By contrast, the perirhinal cortex mediates spatial memory retention [28] and is also crucial for the discrimination and memorization of novel and familiar individual objects [29]. In addition, the parietal cortex is essential for long-term spatial memory [30] and object recognition [31] in rats. "
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