Sandner G, Schmitt P, Karli P
Physiol Behav. 1987;39(3):333-9. doi: 10.1016/0031-9384(87)90231-9.
Rats readily learn to escape from a stimulation applied to most mesencephalic periaqueductal gray (PAG) sites. In the present study, we tried to find out to what extent the differential effects induced by such stimulations actually reflect the existence of intraPAG functional subdivisions. To that end, a row of five electrodes was implanted into the PAG of each of 29 rats. Two kinds of effects were analyzed, the stimulation-elicited overt behaviors and the generalization of switch-off responding from one stimulation site to the others. Further, switch-off latency versus interpulse interval (IPI) relationships were established and both the threshold IPIs and the ceiling switch-off latencies were determined. The most commonly elicited behaviors (jumping, rearing and squealing) as well as the threshold IPIs and the ceiling switch-off latencies were mapped within the PAG. Switch-off behavior was elicited from all the stimulation sites studied. However, in the dorsal PAG the switch-off latency was found to decrease more steeply with decreasing IPI than it did in the ventral PAG. Switch-off generalization was less frequently observed between dorsally located stimulation sites. Jumps were most often elicited from dorsally and rostrally located PAG sites while squeals were more frequently elicited from the caudal part of the PAG and rearings from PAG subareas surrounding the aqueduct.
大鼠很容易学会逃离施加于中脑导水管周围灰质（PAG）大多数部位的刺激。在本研究中，我们试图弄清楚这种刺激所诱导的不同效应在多大程度上实际反映了PAG内功能亚区的存在。为此，将一排五个电极植入29只大鼠每只的PAG中。分析了两种效应，即刺激引发的明显行为以及从一个刺激部位到其他部位的关断反应的泛化。此外，建立了关断潜伏期与脉冲间隔（IPI）的关系，并确定了阈值IPI和上限关断潜伏期。在PAG内绘制了最常引发的行为（跳跃、直立和尖叫）以及阈值IPI和上限关断潜伏期。在所研究的所有刺激部位都引发了关断行为。然而，在背侧PAG中，随着IPI的减小，关断潜伏期的下降比腹侧PAG更陡峭。在背侧刺激部位之间较少观察到关断泛化。跳跃最常由背侧和嘴侧的PAG部位引发，而尖叫更频繁地由PAG的尾侧部分引发，直立则由围绕导水管的PAG亚区引发。
