Maisonnette S S, Kawasaki M C, Coimbra N C, Brandão M L
Laboratório de Psicobiologia, Faculdade Filosofia, Universidade de São Paulo, Brasil.
Brain Res Bull. 1996;40(2):93-8. doi: 10.1016/0361-9230(95)02136-1.
Stimulation of the central nucleus of the inferior colliculus causes defensive behavior. In this work we examined the influence of lesions of brain structures involved in the expression of fear, such as periaqueductal gray matter, amygdala, and substantia nigra pars reticulata (SNpr), on these aversive responses. Thus, rats were implanted with an electrode in the central nucleus of the inferior colliculus, for the determination of the thresholds of alertness, freezing, and escape responses. Each rat also bore a cannula implanted in the periaqueductal, amygdala or Snpr for injection of the neurotoxin N-methyl-D-aspartate (8 micrograms/0.8 microliters). The data obtained show that lesion of the central nucleus of the amygdala increases the thresholds of aversive responses whereas lesion of the basolateral complex decreases the threshold of these responses. Lesion of the Snpr increased the aversive consequences of the electrical stimulation of the inferior colliculus whereas periaqueductal gray lesions, either dorsal or ventral regions, did not change these responses. From the evidences obtained in this work, it is suggested that the expression of the defensive behavior induced by activation of the neural substrates of the inferior colliculus does not seem to depend on the integrity of the periaqueductal gray. On the contrary, the basolateral complex inhibits and the central nucleus amplifies the aversive responses integrated in the inferior colliculus. Furthermore, SNpr seems also to be an important motor output for the defensive behavior induced by stimulation of the inferior colliculus, in agreement with what has been suggested for other brain structures implicated in the expression of fear.
刺激下丘中央核会引发防御行为。在本研究中，我们检测了参与恐惧表达的脑结构损伤，如导水管周围灰质、杏仁核和黑质网状部（SNpr），对这些厌恶反应的影响。因此，给大鼠在下丘中央核植入电极，以测定警觉、僵住和逃避反应的阈值。每只大鼠还在导水管周围、杏仁核或SNpr植入套管，用于注射神经毒素N - 甲基 - D - 天冬氨酸（8微克/0.8微升）。所获得的数据表明，杏仁核中央核损伤会提高厌恶反应的阈值，而基底外侧复合体损伤则会降低这些反应的阈值。SNpr损伤增加了下丘电刺激的厌恶后果，而导水管周围灰质损伤，无论是背侧还是腹侧区域，均未改变这些反应。从本研究获得的证据来看，提示下丘神经基质激活所诱导的防御行为表达似乎并不依赖于导水管周围灰质的完整性。相反，基底外侧复合体抑制而下丘中央核放大在下丘整合的厌恶反应。此外，SNpr似乎也是下丘刺激所诱导的防御行为的重要运动输出，这与其他参与恐惧表达的脑结构所提示的情况一致。
