The release of dopamine (DA) regulates rewarding behavior and motor actions through striatum-targeting efferents from ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). Here, we map and functionally characterize axonal projections from oxytocin neurons in the hypothalamic paraventricular nucleus to midbrain DA regions. Electrophysiological recordings of DA neurons reveal that both the application of oxytocin and optogenetic stimulation of oxytocinergic terminals suffice to increase DA neuron activity in the VTA but downregulate it in SNc. This biased modulation is mediated by oxytocin and vasopressin G-protein-coupled receptors. Oxytocin release directly activates DA neurons and indirectly inhibits them through local GABA neurons, but the relative magnitudes of the two mechanisms differ in VTA and SNc. Oxytocin-modulated DA neurons give rise to canonical striatal projections. Since hypothalamic oxytocinergic projections also target the striatum, oxytocin is poised to bias the balance of DA tone through multiple sites in vertebrate reward circuits.
Key points Auditory brainstem neurons of all vertebrates fire phase‐locked action potentials (APs) at high rates with remarkable fidelity, a process controlled by specialized anatomical and biophysical properties.This is especially true in the avian nucleus magnocellularis (NM) – the analogue of the mammalian anteroventral cochlear nucleus.In addition to high voltage‐activated potassium (KHVA) channels, we report, using whole cell physiology and modelling, that resurgent sodium current (I NaR) of sodium channels (NaV) is equally important and operates synergistically with KHVA channels to enable rapid AP firing in NM.Anatomically, we detected strong NaV1.6 expression near hearing maturation, which was less distinct during hearing development despite functional evidence of I NaR, suggesting that multiple NaV channel subtypes may contribute to I NaR.We conclude that I NaR plays an important role in regulating rapid AP firing for NM neurons, a property that may be evolutionarily conserved for functions related to similar avian and mammalian hearing. AbstractAuditory brainstem neurons are functionally primed to fire action potentials (APs) at markedly high rates in order to rapidly encode the acoustic information of sound. This specialization is critical for survival and the comprehension of behaviourally relevant communication functions, including sound localization and distinguishing speech from noise. Here, we investigated underlying ion channel mechanisms essential for high‐rate AP firing in neurons of the chicken nucleus magnocellularis (NM) – the avian analogue of bushy cells of the mammalian anteroventral cochlear nucleus. In addition to the established function of high voltage‐activated potassium channels, we found that resurgent sodium current (I NaR) plays a role in regulating rapid firing activity of late‐developing (embryonic (E) days 19–21) NM neurons. I NaR of late‐developing NM neurons showed similar properties to mammalian neurons in that its unique mechanism of an ‘open channel block state’ facilitated the recovery and increased the availability of sodium (NaV) channels after depolarization. Using a computational model of NM neurons, we demonstrated that removal of I NaR reduced high‐rate AP firing. We found weak I NaR during a prehearing period (E11–12), which transformed to resemble late‐developing I NaR properties around hearing onset (E14–16). Anatomically, we detected strong NaV1.6 expression near maturation, which became increasingly less distinct at hearing onset and prehearing periods, suggesting that multiple NaV channel subtypes may contribute to I NaR during development. We conclude that I NaR plays an important role in regulating rapid AP firing for NM neurons, a property that may be evolutionarily conserved for functions related to similar avian and mammalian hearing.
PurposeTo evaluate the outcomes of patients who underwent thoracoscopic wedge resection without chest drain placement.MethodsThe subjects of this retrospective study were 89 patients, who underwent thoracoscopic wedge resection at our hospital between January, 2013 and July, 2015. A total of 45 patients whose underlying condition did not meet the following criteria were assigned to the “chest drain placement group” (group A): peripheral lesions, healthy lung parenchyma, no intraoperative air leaks, hemorrhage or effusion accumulation, and no pleural adhesion. The other 44 patients whose underlying condition met the criteria were assigned to the “no chest drain placement group” (group B). Patient characteristics, specimen data, and postoperative conditions were analyzed and compared between the groups.ResultsGroup A patients had poorer forced expiratory volume in one second (FEV1) values, less normal spirometric results, significantly higher resected lung volume, a greater maximum tumor-pleura distance, and a larger maximum tumor size. They also had a longer postoperative hospital stay. There was no difference between the two groups in postoperative complications.ConclusionsAvoiding chest drain placement after a thoracoscopic wedge resection appears to be safe and beneficial for patients who have small peripheral lesions and healthy lung parenchyma.
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