Aamodt S M, Nordeen E J, Nordeen K W
Department of Brain and Cognitive Sciences, University of Rochester, New York 14627, USA.
Neurobiol Learn Mem. 1996 Jan;65(1):91-8. doi: 10.1006/nlme.1996.0010.
Juvenile zebra finches (Poephila guttata) learn their courtship song by memorizing and then reproducing the song of an adult male. Several brain regions involved in song behavior contain N-methyl-D-aspartate (NMDA) receptors, and within one brain nucleus necessary for normal song development, the density of these receptors is twice as high in juveniles that are learning song then in adults that can no longer modify their songs. To determine whether NMDA receptor activation is necessary for normal song development, juvenile zebra finches were systemically injected with the NMDA receptor antagonist MK-801 (0.1 mg/kg) before exposure to an adult male tutor. One control group received the same number of MK-801 injections 24 h out of phase with tutoring, and another received saline before tutoring. In adulthood, birds given MK-801 before tutoring showed little evidence of learning from the tutor, and their songs contained abnormal syllables typical of untutored birds. In contrast, all control birds developed normal songs and copied an average of 72.5% of the tutor's syllables. Acute injections of MK-801 did not alter auditory brainstem evoked potentials in juveniles, indicating that the behavioral effects of MK-801 on song learning were not due to temporary hearing loss. Our results suggest that normal song development in juvenile zebra finches requires NMDA receptor activation during song model presentation.
幼年斑胸草雀（Poephila guttata）通过记忆并随后模仿成年雄雀的歌声来学习求偶鸣叫。参与鸣叫行为的几个脑区含有N-甲基-D-天冬氨酸（NMDA）受体，在正常鸣叫发育所必需的一个脑核内，这些受体的密度在正在学习鸣叫的幼鸟中是那些不再能修改其鸣叫的成年鸟的两倍。为了确定NMDA受体激活对于正常鸣叫发育是否必要，在让幼年斑胸草雀接触成年雄雀“导师”之前，对它们进行了NMDA受体拮抗剂MK-801（0.1毫克/千克）的全身注射。一个对照组在与“导师”指导不同步的24小时内接受相同次数的MK-801注射，另一个对照组在接受指导前注射生理盐水。在成年期，在接受指导前注射MK-801的鸟几乎没有从“导师”那里学习的迹象，它们的歌声包含了未接受指导的鸟所特有的异常音节。相比之下，所有对照鸟都发育出了正常的歌声，平均模仿了“导师”72.5%的音节。对幼鸟急性注射MK-801并没有改变听觉脑干诱发电位，这表明MK-801对鸣叫学习的行为影响不是由于暂时的听力丧失。我们的结果表明，幼年斑胸草雀的正常鸣叫发育在歌声模型呈现期间需要NMDA受体激活。
