Simple nervous system approach to the mechanisms of associative learning

点击翻译按钮获取中文摘要

This work was aimed at clarifying the mechanisms of leaning and memory using physiological and molecular biological methods. First, physiological recordings were made in the procerebrum, which is the olfactory center of the slug, in isolated bran preparations after odor-taste associative conditioning Optical recording of the membrane potential revealed that a cluster of neurons in the procerebrum depolarizes selectively in response to leaned odors.By the mRNA differential display method, we found a gene whose expression elevated specifically after odor-taste associative conditioning, and its sequence has been determined. This gene encoded 121 amino acids, and named LAPS18. To clarify its function, the expression pattern of this gene was determined. The expression of the LAPS18 protein was significantly increased 12-48 h after conditioning compared to the control group. This suggests that the LAPS18 protein is related to the late phase events of learning. Immunohistochemical analysis indicated that LAPS18 protein was present in the entire procerebrum, and localized to the neuropil layers of the procerebrum after conditioning, indicating a conditioning-specific changes in localization. By corUoca1 laser scanning microscopy, the LAPS18 protein was found to be localized to the nerve terminals, especially regions of cell contact. These results suggest that the LAPS18 protein is an extrace11ular matrix protein secreted at nerve terminals and modulate the synaptic connections. The homologue genes of LAPS18 were found in various Vertebrate species. Therefore, LAPS18 was thought to play essential roles in learning and memory.