Spatial learning and memory enables individuals to orientate themselves in an external environment. Synaptic stimulation of dendritic spines on hippocampal place cells underlies adaptive cognitive performance, inducing plastic changes such as spinogenesis, pruning and structural interconversion. Such plastic changes are driven by complex molecular machinery that relies on several actin cytoskeleton-associated proteins (ACAP's), these interacting with actin filaments in the postsynaptic density to guide the conformational changes to spines in accordance with the synaptic information they receive. However, the specific dynamics of the plastic changes in spines driven by ACAP's are poorly understood. Adult rats exhibit efficient allocentric reference memory 30 days after training in a spatial learning paradigm in the Morris water maze. A Golgi study revealed this behavior to be associated with a reduction in both spine density and in mushroom spines, as well as a concomitant increase in thin spines. These changes were accompanied by the overexpression of mRNA encoding β-actin, Spinophilin and Cortactin, whilst the expression of Profilin, α-actinin, Drebrin, Synaptopodin and Myosin decreased. By contrast, no changes were evident in Cofilin, Gelsolin and Arp2/3 mRNA. From this analysis, it appears that neither spinogenesis nor new mushroom spines are necessary for long-term spatial information retrieval, while thin spines could be potentiated to retrieve pre-learned spatial information. Further studies that focus on the signaling pathways and their related molecules may shed further light on the molecular dynamics of the plastic changes to dendritic spines that underlie cognitive performance, both under normal and pathological conditions.

中文翻译：

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对树突棘中细胞骨架相关蛋白的修饰是长期参考记忆所涉及的适应性可塑性的基础。

空间学习和记忆使个人能够将自己定位在外部环境中。突触刺激海马地方细胞上的树突棘奠定了适应性认知能力的基础，诱导了塑性变化，如棘突形成，修剪和结构互变。这种塑性变化是由依赖于几种肌动蛋白细胞骨架相关蛋白（ACAP）的复杂分子机制驱动的，这些蛋白与突触后密度中的肌动蛋白丝相互作用，从而根据所收到的突触信息将构象变化引导至棘突。但是，人们对由ACAP驱动的脊柱塑性变化的具体动力学了解甚少。成年大鼠在莫里斯水迷宫中的空间学习范例中训练后30天，表现出有效的异源参考记忆。高尔基（Golgi）的一项研究表明，这种行为与脊椎密度和蘑菇棘刺的减少有关，同时也与瘦刺的增加有关。这些变化伴随着编码β-肌动蛋白，Spinophilin和Cortactin的mRNA的过表达，而Profilin，α-肌动蛋白，Drebrin，Synaptopodin和Myosin的表达下降。相比之下，Cofilin，凝溶胶蛋白和Arp2 / 3 mRNA没有明显变化。从该分析看来，对于长期的空间信息检索而言，既不需要旋转发生也不需要新的蘑菇刺，而细的刺可以被增强来检索预先学习的空间信息。