Lu Pen-Li, Tsai Meng-Li, Jaw Fu-Shan, Yen Chen-Tung
Institute of Biomedical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taibei, 10617, Taiwan.
Department of Biomechatronic Engineering, National Ilan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 26047, Taiwan.
J Physiol Sci. 2019 Mar;69(2):387-397. doi: 10.1007/s12576-018-00656-3. Epub 2019 Jan 3.
Mediodorsal thalamic nucleus (MD) is a critical relay of nociception. This study recorded responses of MD neurons to noxious mechanical and thermal stimuli in isoflurane anesthetized rats. We found the threshold of noxious mechanical stimulation was 141 gw and that of noxious heat stimulation was 46 °C. A significantly higher percentage of noxious inhibitory neurons were found in the medial and central part of the MD, whereas a higher percentage of noxious excitatory neurons were found in the lateral part of the MD and adjacent intralaminar nuclei. The differential distribution of excitatory and inhibitory neurons implies functional differentiation between the medial and lateral part of the MD in nociception processing. Furthermore, by an analysis of the stimulus-response function (SRF), we found 80% of these excitatory neurons had a step-function or hat-shape-like SRF. This suggests that most of the MD neurons may serve as a system to distinguish innocuous versus noxious stimuli.
丘脑背内侧核（MD）是伤害感受的关键中继站。本研究记录了异氟烷麻醉大鼠中MD神经元对有害机械和热刺激的反应。我们发现有害机械刺激的阈值为141 gw，有害热刺激的阈值为46℃。在MD的内侧和中央部分发现有害抑制性神经元的比例显著更高，而在MD的外侧部分和相邻的板内核中发现有害兴奋性神经元的比例更高。兴奋性和抑制性神经元的差异分布意味着MD内侧和外侧部分在伤害感受处理中的功能分化。此外，通过对刺激-反应函数（SRF）的分析，我们发现这些兴奋性神经元中有80%具有阶跃函数或帽状SRF。这表明大多数MD神经元可能作为一个区分无害与有害刺激的系统。
