Hájos N, Mody I
Department of Neurology and Physiology, Reed Neurological Research Center, University of California, Los Angeles, School of Medicine, Los Angeles, California 90095-1769, USA.
J Neurosci. 1997 Nov 1;17(21):8427-42. doi: 10.1523/JNEUROSCI.17-21-08427.1997.
The properties of spontaneous IPSCs (sIPSCs) recorded with whole-cell patch-clamp techniques were investigated in various anatomically identified hippocampal CA1 interneurons and were compared with those recorded in pyramidal cells. Neurons labeled with biocytin or neurobiotin were classified on the basis of their dendritic and axonal arborizations, leading to the identification of previously unknown interneuron types projecting to the dendritic region of pyramidal cells. In most interneurons, the average sIPSCs decayed slower than did those observed in pyramidal cells. The properties of sIPSCs were homogeneous within a given morphologically identified neuron type. Many interneurons had comparable somatic size, location, and dendritic arbor but displayed extremely different axonal projections paralleled by distinct sIPSC properties. Thus, physiological comparisons are only meaningful after the complete morphological identification of the recorded cells. The decay of sIPSCs matched for amplitudes and rise times could vary over 10-fold in a given interneuron, consistent with electrotonic filtering and possibly with different GABAA receptor subunit assemblies present at distinct synapses. Our findings demonstrate an extensive connectivity among hippocampal interneurons through GABAA synapses of various properties that may underlie complex network oscillations at different frequencies.
采用全细胞膜片钳技术记录的自发性抑制性突触后电流（sIPSCs）特性，在多种经解剖学鉴定的海马CA1中间神经元中进行了研究，并与在锥体细胞中记录的特性进行了比较。用生物素或神经生物素标记的神经元根据其树突和轴突分支进行分类，从而鉴定出以前未知的投射到锥体细胞树突区域的中间神经元类型。在大多数中间神经元中，平均sIPSCs的衰减比在锥体细胞中观察到的要慢。在给定的形态学鉴定的神经元类型中，sIPSCs的特性是均匀的。许多中间神经元具有相当的体细胞大小、位置和树突分支，但显示出极其不同的轴突投射，同时伴有不同的sIPSC特性。因此，只有在对记录的细胞进行完整的形态学鉴定后，生理比较才有意义。在给定的中间神经元中，幅度和上升时间匹配的sIPSCs的衰减可能相差10倍以上，这与电紧张性滤波一致，也可能与不同突触处存在的不同GABAA受体亚基组合有关。我们的研究结果表明，海马中间神经元之间通过各种特性的GABAA突触存在广泛的连接，这可能是不同频率复杂网络振荡的基础。
