Cabrera Guillermo, Cavelli Matías, Lopez Carolina, Rodriguez-Servetti Zulma, Vanini Giancarlo, Chase Michael H, Falconi Atilio, Torterolo Pablo
Laboratory of Sleep Neurobiology, Department of Physiology, School of Medicine, Universidad de la República, Montevideo, Uruguay.
Behav Brain Res. 2013 Nov 1;256:82-94. doi: 10.1016/j.bbr.2013.07.049. Epub 2013 Aug 7.
The inferior colliculus (IC) is a mesencephalic auditory nucleus involved in several functions including the analysis of the frequency and intensity of sounds as well as sound localization. In addition to auditory processes, the IC controls the expression of defensive responses. The objective of the present study was to test the hypothesis that the IC contributes to the maintenance of wakefulness. For this purpose, several experimental approaches were performed in urethane-anesthetized guinea pigs. Electrical or chemical stimulation of the IC resulted in electroencephalographic (EEG) desynchronization, theta rhythm in the hippocampus and an increase in heart rate; all of these effects suggest an arousal reaction. Furthermore, by means of extracellular unit recordings, we determined that most IC neurons increased their spontaneous and tone-evoked responses in association with EEG desynchronization. We also studied the effect on sleep and wakefulness of bilateral acute inhibition of the IC by microinjections of muscimol (a GABAA agonist), as well as the effect of bilateral IC lesions in chronically-instrumented (drug-free) guinea pigs. Acute (via muscimol microinjections), but not chronic (via electrolytic lesions) inhibition of the IC decreased wakefulness., We conclude that the IC plays an active role in the maintenance of wakefulness. Further, we propose that this nucleus may mediate arousal responses induced by biologically significant sounds.
下丘（IC）是中脑听觉核，参与多种功能，包括声音频率和强度分析以及声音定位。除听觉过程外，下丘还控制防御反应的表达。本研究的目的是检验下丘有助于维持觉醒的假说。为此，在氨基甲酸乙酯麻醉的豚鼠身上进行了几种实验方法。对下丘进行电刺激或化学刺激会导致脑电图（EEG）去同步化、海马体中的θ节律以及心率增加；所有这些效应都表明有唤醒反应。此外，通过细胞外单位记录，我们确定大多数下丘神经元在EEG去同步化时会增加其自发反应和音调诱发反应。我们还研究了通过微量注射蝇蕈醇（一种GABAA激动剂）对下丘进行双侧急性抑制对睡眠和觉醒的影响，以及对长期植入仪器（无药物）的豚鼠进行双侧下丘损伤的影响。急性（通过微量注射蝇蕈醇）而非慢性（通过电解损伤）抑制下丘会减少觉醒。我们得出结论，下丘在维持觉醒中起积极作用。此外，我们提出该核可能介导由生物学上重要的声音引起的唤醒反应。
