Daisley J N, Gruss M, Rose S P, Braun K
Brain Research Group, Open University, UK.
Neural Plast. 1998 Jul-Sep;6(3):53-61. doi: 10.1155/NP.1998.53.
In the young chick, the intermediate medial hyperstriatum ventrale is involved in learning paradigms, including imprinting and passive avoidance learning. Biochemical changes in the intermediate medial hyperstriatum ventrale following learning include an up-regulation of amino-acid transmitter levels and receptor activity. To follow the changes of extracellular amino acid levels during passive avoidance training, we used an in vivo microdialysis technique. Probes were implanted in chicks before training the animals, either on a methylanthranylate- or water-coated bead. One hour later, recall was tested in both groups by presenting a similar bead. An increase of extracellular glutamate levels accompanied training and testing in both groups; during training, glutamate release was higher in methylanthranylate-trained than in water-trained chicks. When compared with the methylanthranylate-trained chicks during testing, the water-trained chicks showed enhanced extra-cellular glutamate levels. No other amino acid examined showed significant changes. After testing, the chicks were anesthetized and release-stimulated with an infusion of 50 mM potassium. Extracellular glutamate and taurine levels were significantly increased in both methylanthranylate- and water-trained chicks. The presentation of methylanthranylate as an olfactory stimulus significantly enhanced glutamate levels, especially in methylanthranylate-trained chicks. The results suggest that such changes in extracellular glutamate levels in the intermediate medial hyperstriatum ventrale accompany pecking at either the water- or the methylanthranylate-bead. The taste of the aversant may be responsible for the greater increases found in methylanthranylate-trained birds.
在幼雏中，中间内侧腹侧超纹状体参与学习模式，包括印记学习和被动回避学习。学习后中间内侧腹侧超纹状体的生化变化包括氨基酸递质水平和受体活性的上调。为了追踪被动回避训练期间细胞外氨基酸水平的变化，我们使用了体内微透析技术。在训练动物之前，将探针植入雏鸡体内，探针要么包被在邻氨基苯甲酸甲酯珠子上，要么包被在水珠子上。一小时后，通过呈现类似的珠子对两组进行记忆测试。两组在训练和测试过程中细胞外谷氨酸水平均升高；在训练期间，邻氨基苯甲酸甲酯训练组的谷氨酸释放量高于水训练组的雏鸡。与测试期间邻氨基苯甲酸甲酯训练组的雏鸡相比，水训练组的雏鸡细胞外谷氨酸水平升高。所检测的其他氨基酸均未显示出显著变化。测试后，对雏鸡进行麻醉，并通过注入50 mM钾来刺激释放。邻氨基苯甲酸甲酯训练组和水训练组的雏鸡细胞外谷氨酸和牛磺酸水平均显著升高。邻氨基苯甲酸甲酯作为嗅觉刺激物的呈现显著提高了谷氨酸水平，尤其是在邻氨基苯甲酸甲酯训练组的雏鸡中。结果表明，中间内侧腹侧超纹状体中细胞外谷氨酸水平的这种变化伴随着对水珠子或邻氨基苯甲酸甲酯珠子的啄食。厌恶刺激的味道可能是邻氨基苯甲酸甲酯训练组鸟类中谷氨酸水平升高幅度更大的原因。
