Locus Ceruleus activation suppresses feedforward Interneurons and reduces β-γ electroencephalogram frequencies while it enhances θ frequencies in rat dentate gyrus
Locus Ceruleus activation suppresses feedforward Interneurons and reduces β-γ electroencephalogram frequencies while it enhances θ frequencies in rat dentate gyrus
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DOI：
10.1523/jneurosci.4307-04.2005
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发表时间：
2005-02-23
影响因子：
5.3
通讯作者：
Harley, CW
中科院分区：
文献类型：
--
作者：
Brown, RAM;Walling, SG;Harley, CW
蓝斑被新的刺激激活，它的激活促进学习和记忆。谷氨酸对蓝斑神经元的阶段性激活增强了齿状回种群尖峰振幅，并导致24小时后记录的突触反应的长期增强。在细胞网络水平上，去甲肾上腺素的增强作用是如何介导的尚不清楚。先前的研究表明外源性去甲肾上腺素增强齿状回的抑制性中间神经元放电。这一发现似乎与增强作用的证据不一致。在本研究中，我们记录了氨基甲酸乙酯麻醉大鼠齿状回的脑电图，并在生理上鉴定了齿状回的中间神经元，以谷氨酸激活蓝斑区诱导去甲肾上腺素的自然释放。前馈神经元被蓝斑激活抑制（类似于1 - 2分钟）。反馈中间神经元的活动增加和减少，而颗粒细胞的放电增加，这与诱发电位研究预测的结果一致。脑电图结果与蓝斑激活时的θ波功率增加（4 - 8 Hz）一致，但谷氨酸能蓝斑激活的效果是短暂的（类似于1 - 2分钟）。- γ频率也被暂时抑制。综上所述，这些数据表明，蓝核座激活通过减少前馈抑制性神经元间活动来增强伴随感觉输入的吞吐量，这可能会减少现有细胞组合的“结合”，并通过解除抑制、促进4 - 8 Hz theta和去甲肾上腺素能增强来增强突触可塑性的条件，以促进新表征的建立。
The locus ceruleus is activated by novel stimuli, and its activation promotes learning and memory. Phasic activation of locus ceruleus neurons by glutamate enhances the dentate gyrus population spike amplitude and results in long- term potentiation of synaptic responses recorded after 24 h. Cholinergic activation of locus ceruleus neurons increases hippocampal theta. At the level of the cellular network, it is not clear how the potentiating effects of norepinephrine are mediated. Previous studies show that exogenous norepinephrine enhances inhibitory interneuron firing in the dentate gyrus. This finding appears at odds with evidence for potentiation. In this study, natural release of norepinephrine was induced by glutamate activation of locus ceruleus while we recorded EEGs and physiologically identified interneurons in the dentate gyrus of urethane- anesthetized rats. Feedforward neurons were inhibited ( similar to 1 - 2 min) by locus ceruleus activation. Feedback interneurons showed both increased and decreased activity, whereas granule cells increased firing as predicted by evoked potential studies. EEG results replicated an increase in theta power ( 4 - 8 Hz) with locus ceruleus activation, but the effect with glutamatergic locus ceruleus activation was transient ( similar to 1 - 2 min). beta - gamma Frequencies were also transiently suppressed. Together, the data suggest that locus ceruleus activation enhances the throughput of concomitant sensory input by reducing feedforward inhibitory interneuron activity, which may reduce " binding" in existing cell assemblies, and enhances the conditions for synaptic plasticity through disinhibition, promotion of 4 - 8 Hz theta, and noradrenergic potentiation to facilitate the building of new representations.