GABAergic inhibition shapes temporal and spatial response properties of pyramidal cells in the electrosensory lateral line lobe of gymnotiform fish.
GABAergic inhibition shapes temporal and spatial response properties of pyramidal cells in the electrosensory lateral line lobe of gymnotiform fish.
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GABA 能抑制塑造裸形鱼电感觉侧线叶中锥体细胞的时间和空间响应特性。
DOI：
10.1007/bf00612998
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Maler,L
中科院分区：
文献类型：
--
作者：
Shumway,CA;Maler,L
1.弱电裸体鱼(Eigenmania)一阶核团--电感觉侧线叶(ELL)的幅度编码锥体神经元表现出两种主要的初级传入传入的生理变化。锥体细胞迅速适应幅度的阶跃变化，它们有一个中心/周围的感受野组织。本研究探讨了GABA能抑制对锥体细胞的生理作用。锥体细胞的GABA能突触主要来源于颗粒细胞间神经元，并伴随着递减的输入。2.锥体细胞可分为两种不同的生理类型：E单位和I单位，E单位受刺激幅度的增加而兴奋，I单位受刺激幅度的增加抑制。在两种类型的锥体细胞上应用微离子电泳法将适应时间常数增加70-90%，该时间常数被定义为神经元的反应衰减到其最大值的37%所需的时间。刺激幅度每增加一步，E单位的最大放电频率增加49%，而I单位的放电频率没有明显变化。3.荷包牡丹碱的应用表明，GABA能抑制可能有助于E和I反应特性的严格分离。在荷包牡丹碱存在下，许多E单位(正常情况下仅由刺激幅度增加而兴奋)被增加和降低同时兴奋；许多I单位(正常情况下仅由幅度降低引起)兴奋而增加。4.荷包牡丹碱不影响E单位兴奋性感受野的大小，尽管反应幅度增加。荷包牡丹碱可使抑制环境在空间范围内增加175%。在荷包牡丹碱存在下，I单位感受野中心的大小和反应幅度都没有改变。然而，I单位的对抗性周围增加了49%。5.ELL的解剖很容易理解(见Carr和Maler 1986)。本研究中获得的生理学结果，以及Bastian(1986a，b)的结果，进一步加深了我们对ELL回路的功能作用的理解。我们的结果表明，锥体细胞的空间和时间反应特性受到不同但相互作用的抑制性相互作用神经元的调节，其中一些神经元使用GABA作为神经递质(见图11和12)。这些中间神经元的活动又受下行反馈系统的控制。
1.The amplitude-coding pyramidal neurons of the first-order nucleus in weakly electric gymnotiform fish (Eigenmannia), the electrosensory lateral line lobe (ELL), exhibit 2 major physiological transformations of primary afferent input. Pyramidal cells rapidly adapt to a step change in amplitude, and they have a center/surround receptive-field organization. This study examined the physiological role of GABAergic inhibition on pyramidal cells. GABAergic synapses onto the somata of pyramidal cells primarily originate from granule-cell interneurons along with descending input.2.Pyramidal cells fall into two physiologically distinct categories: E units, which are excited by a rise in stimulus amplitude, and I units, which are inhibited by a rise in stimulus amplitude. Microiontophoretic application of bicuculline methiodide onto both types of pyramidal cells increased the time constant of adaptation, defined as the time required for the neuron's response to decay to 37% of its maximum value, by 70–90%. The peak firing rate of E units to a step increase in stimulus amplitude increased by 49%, while the firing rate of I units did not change significantly.3.Bicuculline application demonstrated that GABAergic inhibition may contribute to the strict segregation of E and I response properties. In the presence of bicuculline, many E units (normally excited only by stimulus amplitude increases) became excited by both increases and decreases; many I units (normally excited only by amplitude decreases) also became excited to increases.4.The size of the excitatory receptive-field of E units was not affected by bicuculline, although response magnitude increased. The inhibitory surround increased in spatial extent by 175% with bicuculline administration. Neither the size of the I unit receptive-field center nor the response magnitude changed in the presence of bicuculline. The antagonistic surround of I units, however, increased by 49%.5.The anatomy of the ELL is well understood (see Carr and Maler 1986). The physiological results obtained in this study, along with the results of Bastian (1986a, b), further our understanding of the functional role of the ELL circuitry. Our results suggest that spatial and temporal response properties of pyramidal cells are regulated by different but interacting inhibitory interneurons, some of which use GABA as a neurotransmitter (see Figs. 11 and 12). The activity of these interneurons is in turn controlled by descending feedback systems.