Sensory Processing mechanisms in periaqueductal gray matter.

用巴比妥酸麻醉的Wistar白化大鼠研究了输导管周围灰质（PAG）神经元的体感觉输入特征。结果表明：(1)PAG神经元可分为两种不同的感受野。一种是大型（PAG-L），另一种是小型（PAG-S）。(2)两种类型的神经元均被非毒性（触觉/热）和毒性（机械、热和化学）刺激激活。(3)绝大多数PAG-L型神经元存在上弦现象。(4)微离子滴注吗啡使PAG-S型神经元的自发活动增加。(5)毒热刺激对PAG-S型神经元的阈值高于对PAG-L型神经元的阈值。

Characteristics of somatosensory inputs to the periaqueductal gray matter (PAG) neurons were investigated using barbiturate-anesthetized Wistar albino rats. Results were as follows :(1) there were at least 2 types of PAG neurons according to their receptive fields. One was large type (PAG-L), and the other was small type (PAG-S).(2) Both types of neurons were activated by nonoxious (touch/ heat) and noxious (mechanical, heat and chemical) stimulation.(3) In a majority of PAG-L type neurons, wind-up phenomenon was observed.(4) Microiontophoretically applied morphine onto the PAG-S type neurons increased their spontaneous activities.(5) The threshold value of noxious heat stimuli applied to the PAG-S type neurons was higher than that applied to the PAG-L type neurons.