Synapses of Horizontal Connections in Adult Rat Somatosensory Cortex Have Different Properties Depending on the Source of their Axons
Synapses of Horizontal Connections in Adult Rat Somatosensory Cortex Have Different Properties Depending on the Source of their Axons
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DOI：
10.1093/cercor/bhp125
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发表时间：
2010-03-01
期刊：
影响因子：
3.7
通讯作者：
Hickmott, Peter W.
中科院分区：
文献类型：
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作者：
Hickmott, Peter W.
在体感皮层 (S1) 中，触觉刺激会激活特定区域。不同身体部位的表征之间的边界限制了兴奋和抑制的传播：从一种表征跨越到另一种表征（跨界，CB）的连接比保留在表征内的连接（非跨界，NCB）弱。因此，使用靠近前爪和下颌表征之间边界的 2/3 层神经元中的全细胞记录来比较 2/3 层锥体神经元上的 CB 和 NCB 突触的生理特性。 CB 和 NCB 连接的电刺激用于激活突触电位。使用 3 种方法确定兴奋性 (EPSP) 和抑制性 (IPSP) 突触后电位 (PSP) 的特性：1) 最小刺激引起单纤维反应； 2) 在细胞外 Sr2+ 存在的情况下进行刺激，以引发异步量子反应； 3) 不同频率的短刺激序列以检查突触后电位 (PSP) 动态。 CB 刺激引起的最小和异步量子 EPSP 均小于 NCB 刺激。然而，在 CB 和 NCB 刺激之间，EPSP 和 IPSP 序列的动态并没有不同。这些数据表明，来自跨越边界（CB）的连接的单个兴奋性突触的振幅比来自表示内（NCB）的连接的振幅更小，并表明了差异的突触后位点。
In somatosensory cortex (S1) tactile stimulation activates specific regions. The borders between representations of different body parts constrain the spread of excitation and inhibition: connections that cross from one representation to another (cross-border, CB) are weaker than those remaining within the representation (noncross border, NCB). Thus, physiological properties of CB and NCB synapses onto layer 2/3 pyramidal neurons were compared using whole-cell recordings in layer 2/3 neurons close to the border between the forepaw and lower jaw representations. Electrical stimulation of CB and NCB connections was used to activate synaptic potentials. Properties of excitatory (EPSPs) and inhibitory (IPSPs) postsynaptic potentials (PSP) were determined using 3 methods: 1) minimal stimulation to elicit single-fiber responses; 2) stimulation in the presence of extracellular Sr2+ to elicit asynchronous quantal responses; 3) short trains of stimulation at various frequencies to examine postsynaptic potential (PSP) dynamics. Both minimal and asynchronous quantal EPSPs were smaller when evoked by CB than NCB stimulation. However, the dynamics of EPSP and IPSP trains were not different between CB and NCB stimulation. These data suggest that individual excitatory synapses from connections that cross a border (CB) have smaller amplitudes than those that come from within a representation (NCB), and suggest a postsynaptic locus for the difference.