Trageser Jason C, Burke Kathryn A, Masri Radi, Li Ying, Sellers Larisa, Keller Asaf
Program in Neuroscience and Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
J Neurophysiol. 2006 Sep;96(3):1456-63. doi: 10.1152/jn.00423.2006. Epub 2006 Jun 14.
We have previously shown that the GABAergic nucleus zona incerta (ZI) suppresses vibrissae-evoked responses in the posterior medial (POm) thalamus of the rodent somatosensory system. We proposed that this inhibitory incerto-thalamic pathway regulates POm responses during different behavioral states. Here we tested the hypothesis that the cholinergic reticular activating system, implicated in regulating states of arousal, modulates ZI activity. We show that stimulation of brain stem cholinergic nuclei (laterodorsal tegmental and pedunculopontine tegmental) results in suppression of spontaneous firing of ZI neurons. Iontophoretic application of the cholinergic agonist carbachol to ZI neurons suppresses both their spontaneous firing and their vibrissae-evoked responses. We also found that carbachol application to an in vitro slice preparation suppresses spontaneous firing of neurons in the ventral sector of ZI (ZIv). Finally, we demonstrate that the majority of ZIv neurons contain parvalbumin and project to POm. Based on these results, we present the state-dependent gating hypothesis, which states that differing behavioral states-regulated by the brain stem cholinergic system-modulate ZI activity, thereby regulating the response properties of higher-order nuclei such as POm.
我们之前已经表明，γ-氨基丁酸能的未定带核（ZI）可抑制啮齿动物体感系统后内侧丘脑（POm）中触须诱发的反应。我们提出，这种抑制性的未定带-丘脑通路在不同行为状态下调节POm的反应。在这里，我们测试了一个假说，即参与调节觉醒状态的胆碱能网状激活系统调节ZI的活动。我们发现，刺激脑干胆碱能核团（外侧背侧被盖核和脚桥被盖核）会导致ZI神经元的自发放电受到抑制。向ZI神经元离子导入胆碱能激动剂卡巴胆碱会抑制其自发放电以及触须诱发的反应。我们还发现，将卡巴胆碱应用于体外脑片标本会抑制ZI腹侧区（ZIv）神经元的自发放电。最后，我们证明，大多数ZIv神经元含有小白蛋白并投射到POm。基于这些结果，我们提出了状态依赖性门控假说，该假说认为，由脑干胆碱能系统调节的不同行为状态会调节ZI的活动，从而调节诸如POm等高级核团的反应特性。
