Wiig K A, Cooper L N, Bear M F
Institute for Brain and Neural Systems, Brown University, Providence, Rhode Island 02912, USA.
Learn Mem. 1996 Nov-Dec;3(4):313-25. doi: 10.1101/lm.3.4.313.
The involvement of the perirhinal cortex and the fornix in retrograde and anterograde amnesia in the rat was investigated in this experiment. Male Sprague-Dawley rats were trained on a series of five visual discrimination problems at distinct time intervals prior to receiving bilateral, electrolytic lesions of the perirhinal cortex or the fornix, combined lesions of both these structures, or sham operations. Following recovery from surgery, rats were retested on the preoperatively learned discrimination problems, as well as learning a new discrimination and discrimination reversal. Results indicated that all animals with lesions exhibited temporally graded retrograde amnesia, whereby memories acquired in the recent past (1-3 weeks) were impaired, and memories acquired in the remote past (6-8 weeks) were spared. There was no difference in the magnitude of retrograde amnesia between the three lesion groups. Animals in the perirhinal, fornix, and combined lesion groups were able to learn a new discrimination problem at a rate comparable to control rats; however, the animals with lesions were impaired at learning the discrimination reversal. The perirhinal, fornix, and combined lesion animals also exhibited a significantly faster forgetting rate over a 2-week retention interval than control rats. These results suggest that medial temporal structures including the perirhinal cortex and the fornix are involved in the consolidation of mnemonic information and that their involvement in this process occurs over a discrete period of time.
本实验研究了大鼠嗅周皮质和穹窿在逆行性和顺行性遗忘中的作用。在雄性Sprague-Dawley大鼠接受嗅周皮质或穹窿的双侧电解损伤、这两个结构的联合损伤或假手术之前，在不同的时间间隔对它们进行一系列五个视觉辨别问题的训练。手术后恢复后，对大鼠进行术前学习的辨别问题的重新测试，以及学习一个新的辨别和辨别反转任务。结果表明，所有有损伤的动物都表现出时间梯度逆行性遗忘，即近期（1 - 3周）获得的记忆受损，而远期（6 - 8周）获得的记忆未受影响。三个损伤组之间逆行性遗忘的程度没有差异。嗅周皮质、穹窿和联合损伤组的动物能够以与对照大鼠相当的速度学习一个新的辨别问题；然而，有损伤的动物在学习辨别反转任务时受损。嗅周皮质、穹窿和联合损伤的动物在2周的保持间隔内也表现出比对照大鼠明显更快的遗忘率。这些结果表明，包括嗅周皮质和穹窿在内的内侧颞叶结构参与记忆信息的巩固，并且它们在这个过程中的参与发生在一个离散的时间段内。
