Discharge patterns of somatosensitive neurons in the nucleus tractus solitarius of the cat.
Discharge patterns of somatosensitive neurons in the nucleus tractus solitarius of the cat.
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猫孤束核体感神经元的放电模式。
DOI：
10.1016/j.neuroscience.2004.12.018
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Waldrop,TG
中科院分区：
文献类型：
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作者：
Potts,JT;Waldrop,TG
孤束核(NTS)神经元对感觉信息的编码尚不完全清楚。在α-氯醛糖-氨基甲酸酯麻醉猫模型上，用细胞外单位记录的方法，研究了电刺激下腰/上腰神经腹根引起的骨骼肌收缩引起的躯体A-δ和C-纤维传入放电的特征。一般来说，躯体传入刺激会引起两种不同的放电模式。第一个群体(36/43个细胞)增加了他们的放电率，以短暂的躯体刺激。其中一个亚群(21/27个细胞)在持续的躯体刺激中表现出其放电率的快速衰减。最大瞬时放电频率(FP)随刺激强度的增加而增加(分别为105±4vs.119±4vs.139±4 Hz，10，20和40 Hz，P<；0.0001)，而稳态放电频率不变(分别为25±2vs.27±2vs.27±2 Hz，10，20和40 Hz，P=0.72)。推导出了两个量化衰减特性的指标。由指数曲线拟合得到的衰减速率常数不受刺激频率的影响(461±10vs.442±14vs.429±26ms，分别为10、20和40赫兹，P=0.415)，衰减指数也不随刺激频率的变化而改变(分别为76±2vs.77±2vs.81±2%、10、20和40赫兹，P=0.187)。相比之下，第二组(43个细胞中的7个)降低了刺激下的放电频率。在压力敏感测试的NTS神经元中(29/36)，没有一个对压力刺激有反应。这些结果已经确定了在持续刺激中表现出快速放电率衰减特性的一组躯体敏感的NTS神经元。然而，在有节奏的躯体感觉输入过程中，这个群体可以忠实地编码相位兴奋。这些结果与躯体感觉输入对压力感受器反射功能的作用有关。
Encoding of sensory information by nucleus of the solitary tract (NTS) neurons is incompletely understood. Using extracellular single-unit recording in α-chloralose-urethane anesthetized cats, we have examined the discharge characteristics of NTS neurons to activation of somatic Aδ and C fiber afferents by skeletal muscle contraction evoked by electrical stimulation of lower lumbar/upper sacral ventral roots. Generally, somatic afferent stimulation evoked two distinct firing patterns. The first population (36/43 cells) increased their firing rate to brief somatic stimuli. A subset (21/27 cells) exhibited a rapid decay of their firing rate during sustained somatic stimulation. Peak instantaneous firing frequency (Fp) increased proportionally with the intensity of somatic stimulation (105±4 vs. 119±4 vs. 139±4 Hz, 10, 20 and 40 Hz, respectively, P<0.0001), whereas steady-state firing frequency (Fss) was not altered (25±2 vs. 27±2 vs. 27±2 Hz, 10, 20 and 40 Hz, respectively, P=0.72). Two indices were derived to quantify the decay properties. The decay rate constant (obtained from exponential curve fitting) was not altered by stimulation frequency (461±10 vs. 442±14 vs. 429±26 ms, 10, 20 and 40 Hz, respectively, P=0.415), nor was the decay index (derived to express the percent reduction in firing rate with respect to the initial peak firing rate; 76±2 vs. 77±2 vs. 81±2%, 10, 20 and 40 Hz, respectively, P=0.187). In contrast, the second population (seven of 43 cells) decreased their firing rate to stimulation. Of the NTS neurons tested for barosensitivity (29/36), none responded to pressure stimulation. These results have identified a population of somatosensitive NTS neurons that exhibit rapid firing rate decay properties during sustained stimulation. However, this population could faithfully encode phasic excitation during rhythmic somatosensory input. These results are discussed in relation to the role of somatosensory input on baroreflex function.