Synaptic proliferation in the motor cortex of adult cats after long-term thalamic stimulation.
Synaptic proliferation in the motor cortex of adult cats after long-term thalamic stimulation.
复制标题
长期丘脑刺激后成年猫运动皮层的突触增殖。
DOI：
10.1152/jn.1992.68.1.295
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发表时间：
1992
影响因子：
2.5
通讯作者：
Asanuma,H
中科院分区：
文献类型：
--
作者：
Keller,A;Arissian,K;Asanuma,H
1. 关于中枢神经系统中信息存储的一个假设是突触回路中结构变化的诱导。这一假设预测，行为经验产生的神经活动的变化，随后诱导突触发生在成熟的中枢神经系统。现有数据表明，新运动行为的印痕的建立可能涉及初级运动皮层内突触相互作用的改变。本研究检验了一种假设，即突触回路模式和突触激活模式在投射到运动皮层的神经活动增强后重新排列。2. 将电极植入丘脑腹后外侧核（VPL），对行为自由的成年猫的运动皮层进行长期刺激（20微a， 4天）。这种刺激主要影响从体感皮层（2区）到运动皮层4区的皮质输入。采用电子显微镜和体视学方法比较了受刺激（实验）运动皮层第II/III层各种类型突触的数值密度（Nv）与对侧（对照）半球相应突触的数值密度（Nv）。3. 长期刺激使实验运动皮层突触Nv显著增加（25.6%）。这种增加主要是由于树突棘的不对称突触的Nv增加。对称突触和树突轴不对称突触的数量不受长期刺激的影响。4. 突触活跃区（通过测量突触后密度（psd）的长度来计算）在实验运动皮层中明显更长。在树突轴的不对称突触中，psd选择性延长（增加28%）。5. 在实验半球中，psd穿孔突触的Nv明显更高。突触相关的多核糖体的发生率也增加了，这些多核糖体最常见于树突棘的基部。穿孔突触和多核糖体数量的增加都是突触发生的形态学标志。6. 不同曲率（即突触前凹、凸或平）的突触的百分比在实验和控制运动皮层中相似。（摘要删节为400字）
1. One of the hypotheses for information storage in the CNS postulates the induction of structural changes in synaptic circuits. This postulate predicts that behavioral experiences produce changes in neural activity that subsequently induce synaptogenesis in the mature CNS. Available data indicate that the establishment of engrams for novel motor acts may involve alterations of synaptic interactions within the primary motor cortex. The present study examines the hypothesis that patterns of synaptic circuitry and of synaptic activation are rearranged after enhanced neural activity in pathways projecting to the motor cortex. 2. Electrodes implanted in the ventroposterolateral (VPL) nucleus of the thalamus were used for long-term stimulation (20 microA, 4 days) of afferents to the motor cortex in freely behaving, adult cats. This stimulation primarily affected corticocortical inputs from the somatosensory cortex (area 2) to area 4 gamma of the motor cortex. Electron microscopy and stereological procedures were used to compare the numerical density (Nv) of various types of synapses in layers II/III of the stimulated (experimental) motor cortex with the Nv of the corresponding synapses in the contralateral (control) hemisphere. 3. Long-term stimulation produced a significant increase (25.6%) in synaptic Nv in experimental motor cortex. This increase was due primarily to an increase in the Nv of asymmetrical synapses with dendritic spines. The numbers of symmetrical synapses, and of asymmetrical synapses with dendritic shafts, were not affected by long-term stimulation. 4. Synaptic active zones [calculated by measuring the lengths of postsynaptic densities (PSDs)] were significantly longer in experimental motor cortex. Lengthening of PSDs occurred selectively in asymmetrical synapses with dendritic shafts (28% increase). 5. The Nv of synapses having perforations in their PSDs (perforated synapses) was significantly higher in experimental hemispheres. Also increased was the incidence of synapse-associated polyribosomes, which are most commonly found at the base of dendritic spines. An increase in the number of perforated synapses and of polyribosomes are both morphological hallmarks of synaptogenesis. 6. The percentages of synapses having different curvatures (i.e., presynaptically concave, convex, or flat) were similar in experimental and in control motor cortex.(ABSTRACT TRUNCATED AT 400 WORDS)