Differential roles of GABAergic and glycinergic input on FM selectivity in the inferior colliculus of the pallid bat.
Differential roles of GABAergic and glycinergic input on FM selectivity in the inferior colliculus of the pallid bat.
复制标题
GABA 能和甘氨酸能输入对苍白蝙蝠下丘 FM 选择性的不同作用。
DOI：
10.1152/jn.00569.2011
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发表时间：
2011
影响因子：
2.5
通讯作者：
Fuzessery,ZoltanM
中科院分区：
文献类型：
--
作者：
Williams,AnthonyJ;Fuzessery,ZoltanM
多种机制已被证明在苍白蝙蝠的下丘（IC）中央核内形成调频（FM）选择性。在这项研究中，我们关注与边带抑制相关的机制。抑制与激发的相对到达时间可以用来预测双音抑制模式下的调频反应。早期到达的低频抑制（LFI）阻止了对向上扫描的响应，从而形成了方向选择性。迟发高频抑制（HFI）抑制慢频扫频，从而形成向下扫频的速率选择性。采用离子吸附法应用加巴嗪（GBZ）阻断gaba受体或士的宁（Strych）阻断甘氨酸受体，以评估去除抑制对每种形式的FM选择性的影响。GBZ和Strych对FM方向选择性有相似的影响，当两种药物共同应用时，高达86%的神经元的选择性降低。FM速率选择性对药物应用的抗性更强，只有不到38%的神经元受到影响。此外，只有Strych可以消除调频选择性，而单独使用GBZ是无效的。FM选择性的丧失与形成选择性形式的各自抑制边带的丧失直接相关。LFI的消除与调频方向选择性的丧失有关，而HFI的消除与调频速率选择性的丧失有关。结果表明：1)虽然大多数调频方向选择性是在IC内产生的，但大多数速率选择性是从听觉系统的较低层次遗传的；2)LFI的丧失与调频方向选择性的丧失相对应，并且是通过gaba能或甘氨酸能输入产生的；3)HFI的丧失与调频速率选择性的丧失相对应，并且主要是通过甘氨酸能输入产生的。
Multiple mechanisms have been shown to shape frequency-modulated (FM) selectivity within the central nucleus of the inferior colliculus (IC) in the pallid bat. In this study we focus on the mechanisms associated with sideband inhibition. The relative arrival time of inhibition compared with excitation can be used to predict FM responses as measured with a two-tone inhibition paradigm. An early-arriving low-frequency inhibition (LFI) prevents responses to upward sweeps and thus shapes direction selectivity. A late-arriving high-frequency inhibition (HFI) suppresses slow FM sweeps and thus shapes rate selectivity for downward sweeps. Iontophoretic application of gabazine (GBZ) to block GABAAreceptors or strychnine (Strych) to block glycine receptors was used to assess the effects of removal of inhibition on each form of FM selectivity. GBZ and Strych had a similar effect on FM direction selectivity, reducing selectivity in up to 86% of neurons when both drugs were coapplied. FM rate selectivity was more resistant to drug application with less than 38% of neurons affected. In addition, only Strych could eliminate FM rate selectivity, whereas GBZ alone was ineffective. The loss of FM selectivity was directly correlated to a loss of the respective inhibitory sideband that shapes that form of selectivity. The elimination of LFI correlated to a loss of FM direction selectivity, whereas elimination of HFI correlated to a loss of FM rate selectivity. Results indicate that1) although the majority of FM direction selectivity is created within the IC, the majority of rate selectivity is inherited from lower levels of the auditory system,2) a loss of LFI corresponds to a loss of FM direction selectivity and is created through either GABAergic or glycinergic input, and3) a loss of HFI corresponds to a loss of FM rate selectivity and is created mainly through glycinergic input.