Respiration drives network activity and modulates synaptic and circuit processing of lateral inhibition in the olfactory bulb.
Respiration drives network activity and modulates synaptic and circuit processing of lateral inhibition in the olfactory bulb.
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DOI：
10.1523/jneurosci.4278-11.2012
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发表时间：
2012-01-04
期刊：
影响因子：
--
通讯作者：
Shepherd GM
中科院分区：
文献类型：
--
作者：
Phillips ME;Sachdev RN;Willhite DC;Shepherd GM
呼吸在整个嗅觉系统中产生节律活动，驱动嗅觉上皮、嗅球(OB)和皮质中的神经元。这种活动的节律性被认为是感觉加工的关键组成部分。OB投射神经元，二尖瓣和簇状细胞，表现出与呼吸节律性耦合的膜电位的尖峰和阈值下振荡。然而，产生呼吸耦合活动的网络和突触机制以及呼吸对侧向抑制的影响尚不清楚，侧向抑制是OB回路中感觉处理的主要组成部分。二尖瓣和簇生细胞中的呼吸偶联活动是由感觉突触输入产生的，是单独来自鼻腔气流、皮质球反馈，还是投射神经元固有的膜特性？呼吸作用是否促进或调节OB区抑制性侧路的活动？在此，来自麻醉大鼠已识别的二尖瓣和簇生细胞的活体细胞内记录表明，鼻腔气流为这两种细胞提供兴奋性突触输入，并驱动呼吸耦合的尖峰。侧抑制，即球内微刺激诱发的抑制性突触后电位，受呼吸的调节。在单个二尖瓣和簇状细胞中，在特定的呼吸时相抑制较大。然而，在任何一种细胞类型中，在特定的呼吸期内，侧向抑制并不是一致的大。去除鼻腔气流消除了两种细胞中的呼吸耦合尖峰，并几乎消除了二尖瓣中的尖峰，但不能消除簇状细胞。在没有鼻腔气流的情况下，二尖瓣细胞的侧向抑制作用较弱，簇生细胞的侧向抑制作用较小。因此，呼吸驱动不同的网络活动，从功能上调节OB的感觉处理。
Respiration produces rhythmic activity in the entire olfactory system, driving neurons in the olfactory epithelium, bulb (OB) and cortex. The rhythmic nature of this activity is believed to be a critical component of sensory processing. OB projection neurons, mitral and tufted cells, exhibit both spiking and subthreshold membrane potential oscillations rhythmically coupled to respiration. Yet, the network and synaptic mechanisms that produce respiration-coupled activity, and the effects of respiration on lateral inhibition, a major component of sensory processing in OB circuits, are not known. Is respiration-coupled activity in mitral and tufted cells produced by sensory synaptic inputs from nasal airflow alone, cortico-bulbar feedback, or intrinsic membrane properties of the projection neurons? Does respiration facilitate or modulate the activity of inhibitory lateral circuits in the OB? Here, in vivo intracellular recordings from identified mitral and tufted cells in anesthetized rats demonstrate that nasal airflow provides excitatory synaptic inputs to both cell types and drives respiration-coupled spiking. Lateral inhibition, inhibitory post-synaptic potentials evoked by intrabulbar microstimulation, was modulated by respiration. In individual mitral and tufted cells inhibition was larger at specific respiratory phases. However, lateral inhibition was not uniformly larger during a particular respiratory phase in either cell type. Removing nasal airflow abolished respiration-coupled spiking in both cell types and nearly eliminated spiking in mitral, but not tufted cells. In the absence of nasal airflow, lateral inhibition was weaker in mitral cells and less modulated in tufted cells. Thus, respiration drives distinct network activities that functionally modulate sensory processing in the OB.