Melleu Fernando Falkenburger, Lino-de-Oliveira C, Marino-Neto J
Department of Physiological Sciences, CCB, Federal University of Santa Catarina, Florianópolis, SC, 88040-900, Brazil.
Institute of Biomedical Engineering, EEL-CTC, Federal University of Santa Catarina, Florianópolis, SC, 88040-900, Brazil.
Brain Struct Funct. 2017 Apr;222(3):1253-1265. doi: 10.1007/s00429-016-1275-0. Epub 2016 Jul 22.
Tonic immobility (TI) is a response to a predator attack, or other inescapable danger, characterized by immobility, analgesia and unresponsiveness to external stimuli. In mammals, the periaqueductal gray (PAG) and deep tectal regions control the expression of TI as well as other defensive behaviors. In birds, little is known about the mesencephalic circuitry involved in the control of TI. Here, adult pigeons (both sex, n = 4/group), randomly assigned to non-handled, handled or TI groups, were killed 90 min after manipulations and the brains processed for detection of c-Fos immunoreactive cells (c-Fos-ir, marker for neural activity) in the mesencephalic central gray (GCt) and the adjacent nucleus intercollicularis (ICo). The NADPH-diaphorase staining delineated the boundaries of the sub nuclei in the ICo-GCt complex. Compared to non-handled, TI (but not handling) induced c-Fos-ir in NADPH-diaphorase-rich and -poor regions. After TI, the number of c-Fos-ir increased in the caudal and intermediate areas of the ICo (but not in the GCt), throughout the rostrocaudal axis of the dorsal stratum griseum periventriculare (SGPd) of the optic tectum and in the n. mesencephalicus lateralis pars dorsalis (MLd), which is part of the ascending auditory pathway. These data suggest that inescapable threatening stimuli such as TI may recruit neurons in discrete areas of ICo-GCt complex, deep tectal layer and in ascending auditory circuits that may control the expression of defensive behaviors in pigeons. Additionally, data indicate that the contiguous deep tectal SCPd (but not GCt) in birds may be functionally comparable to the mammalian dorsal PAG.
紧张性不动（TI）是对捕食者攻击或其他无法逃避的危险的一种反应，其特征为不动、镇痛以及对外界刺激无反应。在哺乳动物中，中脑导水管周围灰质（PAG）和深部顶盖区域控制着TI以及其他防御行为的表达。在鸟类中，关于参与TI控制的中脑回路知之甚少。在此，将成年鸽子（雌雄均有，每组n = 4只）随机分为未处理组、处理组或TI组，在操作后90分钟处死，对大脑进行处理，以检测中脑中央灰质（GCt）和相邻的顶盖间核（ICo）中c-Fos免疫反应性细胞（c-Fos-ir，神经活动标志物）。NADPH-黄递酶染色勾勒出ICo-GCt复合体中亚核的边界。与未处理组相比，TI（而非处理）在富含和缺乏NADPH-黄递酶的区域诱导了c-Fos-ir。TI后，ICo的尾侧和中间区域（而非GCt）、视顶盖室周灰质背层（SGPd）的整个前后轴以及中脑外侧背侧部（MLd，听觉上行通路的一部分）中的c-Fos-ir数量增加。这些数据表明，诸如TI之类的无法逃避的威胁性刺激可能会募集ICo-GCt复合体、深部顶盖层和听觉上行回路中离散区域的神经元，这些神经元可能控制鸽子防御行为的表达。此外，数据表明鸟类中相邻的深部顶盖SCPd（而非GCt）在功能上可能与哺乳动物的背侧PAG相当。
