Department of Neuroscience, University of Arizona, Tucson, 85721, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2011 Jun;197(6):653-65. doi: 10.1007/s00359-011-0625-x. Epub 2011 Feb 1.
Local interneurons (LNs) play important roles in shaping and modulating the activity of output neurons in primary olfactory centers. Here, we studied the morphological characteristics, odor responses, and neurotransmitter content of LNs in the antennal lobe (AL, the insect primary olfactory center) of the moth Manduca sexta. We found that most LNs are broadly tuned, with all LNs responding to at least one odorant. 70% of the odorants evoked a response, and 22% of the neurons responded to all the odorants tested. Some LNs showed excitatory (35%) or inhibitory (33%) responses only, while 33% of the neurons showed both excitatory and inhibitory responses, depending on the odorant. LNs that only showed inhibitory responses were the most responsive, with 78% of the odorants evoking a response. Neurons were morphologically diverse, with most LNs innervating almost all glomeruli and others innervating restricted portions of the AL. 61 and 39% of LNs were identified as GABA-immunoreactive (GABA-ir) and non-GABA-ir, respectively. We found no correlations between odor responses and GABA-ir, neither between morphology and GABA-ir. These results show that, as observed in other insects, LNs are diverse, which likely determines the complexity of the inhibitory network that regulates AL output.
局部中间神经元（LNs）在塑造和调节初级嗅觉中枢输出神经元的活动方面发挥着重要作用。在这里，我们研究了鳞翅目昆虫烟夜蛾触角叶（AL，昆虫的初级嗅觉中枢）中 LN 的形态特征、气味反应和神经递质含量。我们发现大多数 LN 具有广泛的调谐性，所有 LN 都至少对一种气味有反应。70%的气味剂能引起反应，22%的神经元能对所有测试的气味剂产生反应。有些 LN 只表现出兴奋（35%）或抑制（33%）反应，而 33%的神经元则根据气味剂表现出兴奋和抑制反应。只表现出抑制反应的 LN 反应最强烈，78%的气味剂能引起反应。神经元在形态上具有多样性，大多数 LN 支配几乎所有的肾小球，而其他 LN 则支配 AL 的特定区域。61%和 39%的 LN 分别被鉴定为 GABA 免疫反应（GABA-ir）和非 GABA-ir。我们没有发现气味反应和 GABA-ir 之间、形态和 GABA-ir 之间存在相关性。这些结果表明，与在其他昆虫中观察到的情况一样，LN 是多样化的，这可能决定了调节 AL 输出的抑制性网络的复杂性。
