Ruskov D A, Stewart M G, Davies H A, Harrison E
Department of Biology, Open University, Milton Keynes, U.K.
Neuroscience. 1995 May;66(2):291-307. doi: 10.1016/0306-4522(94)00594-u.
Two regions in the forebrain of domestic chicks (Gallus domesticus), the intermediate and medial hyperstriatum ventrale and the lobus parolfactorius, have previously been shown to be important centres of biochemical, pharmacological and physiological change following one-trial passive avoidance training. The purpose of the present study was to examine, at the electron microscopic level, the fine spatial re-arrangement of synaptic structures in the intermediate and medial hyperstriatum ventrale (at 30 min), and in the lobus parolfactorius (at 24 h), post-training using comprehensive biometrical designs, image analysis and stochastic approaches. In intermediate and medial hyperstriatum ventrale, no significant differences in the numerical density of synapses either between control and trained chicks, or between hemispheres, were revealed using the disector method. However, after training, a nested-ANOVA demonstrated an increase in the thickness of pre- and post-synaptic electron densities (estimated via image analysis) only in the left intermediate and medial hyperstriatum ventrale, whereas synaptic apposition zone profiles increased in length bilaterally. In presynaptic terminals from the intermediate and medial hyperstriatum ventrale, stochastic analysis revealed that training resulted in the re-distribution of synaptic vesicles between two spatial pools relative to synaptic apposition zones, in both hemispheres producing a large number of synaptic vesicles closer to synaptic apposition zones; a nearest neighbour analysis of synaptic apposition zone profiles indicated that the lateral shape of the synaptic apposition zone after training is more complex in both hemispheres. In the lobus parolfactorius at 24 h post-training the main changes in synaptic fine structure involved a shift of synaptic vesicles away from synaptic apposition zones in the right hemisphere with the distance between synaptic apposition zones decreasing; in the left lobus parolfactorius, synaptic apposition zones became more regular/round in shape with a greater distance between them after training. These data suggest that the initial acquisition of memory involves population changes in the fine spatial organization of synaptic vesicles and synaptic apposition zones in synapses in the intermediate and medial hyperstriatum ventrale, which indicate a possible tendency towards greater synaptic efficacies. These changes are as dynamics as the molecular changes which have hitherto been considered the preserve of short-term correlates of memory formation.
家鸡（原鸡）前脑的两个区域，即中内侧腹侧超纹状体和嗅觉旁叶，先前已被证明是单次被动回避训练后生化、药理和生理变化的重要中心。本研究的目的是在电子显微镜水平上，使用综合生物统计学设计、图像分析和随机方法，研究训练后30分钟时中内侧腹侧超纹状体以及训练后24小时时嗅觉旁叶中突触结构的精细空间重排。在中内侧腹侧超纹状体中，使用分割计数法未发现对照鸡和训练鸡之间或半球之间突触的数量密度有显著差异。然而，训练后，嵌套方差分析表明，仅在左侧中内侧腹侧超纹状体中，突触前和突触后电子密度的厚度（通过图像分析估计）增加，而双侧突触并置区轮廓的长度增加。在中内侧腹侧超纹状体的突触前终末，随机分析表明，训练导致两个空间池中的突触小泡相对于突触并置区重新分布，在两个半球中都产生了大量更靠近突触并置区的突触小泡；对突触并置区轮廓的最近邻分析表明，训练后两个半球中突触并置区的外侧形状更复杂。在训练后24小时的嗅觉旁叶中，突触精细结构的主要变化包括右半球中突触小泡从突触并置区移开，突触并置区之间的距离减小；在左侧嗅觉旁叶中，训练后突触并置区的形状变得更规则/更圆，它们之间的距离更大。这些数据表明，记忆的初始获取涉及中内侧腹侧超纹状体中突触小泡和突触并置区精细空间组织的群体变化，这表明可能存在突触效能增强的趋势。这些变化与分子变化一样动态，而分子变化迄今被认为是记忆形成短期相关因素的专属。
