Grant S J, Highfield D A
Department of Psychology, University of Delaware, Newark 19716.
Brain Res. 1991 Sep 13;559(1):64-74. doi: 10.1016/0006-8993(91)90287-6.
The extracellular electrophysiological properties of neurons in the laterodorsal tegmental nucleus (LDT), a major source of cholinergic afferents to the thalamus, were studied in chloral hydrate-anesthetized rats. A combination of antidromic activation from the thalamus and histological verification of recording sites was used to correlate the identity of extracellular recordings in the rat LDT with cholinergic neurons in that region. All neurons antidromically activated by stimulation of the anteroventral thalamus were histologically verified to be within clusters of cholinergic (NADPH-d-positive) cells in the LDT or in the adjacent nucleus locus coeruleus (LC). The thalamically projecting LDT neurons had a homogeneous neurophysiological profile consisting of long duration action potentials (mean = 2.5 ms), slow conduction velocities (mean = 0.78 m/s), and lengthy chronaxie values (mean = 0.725 ms). The appearance and axonal characteristics of these neurons resembled those of noradrenergic LC neurons, but the two populations exhibited substantially different spontaneous activity patterns and sensory responsiveness. These characteristics may be useful in the preliminary identification of putative cholinergic neurons in vivo, and thereby provide a foundation for exploring the neuropharmacology, afferent modulation, sensory responsiveness and behavioral correlates of the brainstem cholinergic system.
在水合氯醛麻醉的大鼠中，研究了丘脑胆碱能传入神经的主要来源——外侧背盖核（LDT）中神经元的细胞外电生理特性。采用从丘脑进行逆向激活并结合记录位点的组织学验证，将大鼠LDT中的细胞外记录身份与该区域的胆碱能神经元相关联。所有通过刺激丘脑前腹侧而被逆向激活的神经元，经组织学验证均位于LDT中胆碱能（NADPH-d阳性）细胞簇内或相邻的蓝斑核（LC）中。投射到丘脑的LDT神经元具有一致的神经生理学特征，包括动作电位持续时间长（平均 = 2.5毫秒）、传导速度慢（平均 = 0.78米/秒）和时值长（平均 = 0.725毫秒）。这些神经元的外观和轴突特征与去甲肾上腺素能LC神经元相似，但这两类神经元表现出明显不同的自发活动模式和感觉反应性。这些特征可能有助于在体内初步识别假定的胆碱能神经元，从而为探索脑干胆碱能系统的神经药理学、传入调制、感觉反应性和行为相关性奠定基础。
