Johnson R N, Englander R N, Quint S R, Hanna G R
Neurol Neurocir Psiquiatr. 1977;18(2-3 Suppl):291-302.
Epilepsy typifies instability in a complex control system. We have previously identified parameters of the thalamocortical motor system of the cat which correlate with epileptiform activity and are controlled by common anticonvulsants. This study is concerned with the control of such parameters by cerebellar stimulation, potencially promoting stability within the motor system. Under computer control, stimuli were delivered to both ventrolateral thalamus and cerebellar cortex, with multichannel recording of evoked responses obtained from sensorimotor cortex. Cortical evoked responses were plotted as an excitability curve (mean response amplitude as a function of pulse interval) or a family of threshold curves (mean response amplitude as a function of stimulus amplitude at various fixed intervals). The present study reveals that cerebellar epidural stimulation can reduce both the height and duration of the excitability curve, as well as increase the response threshold and reduce the saturation level of the threshold curve. The degree and direction of these parameter changes are dependent on the frequency, polarity, and amplitude of cerebellar stimulation, with the amount of parameter change exceeding that achieved by monotoxic doses of anticonvulsants. These data suggest that control of parameters related to excitability and threshold in the thalamocortical motor system may be the means by which cerebellar stimulation accomplishes control of clinical seizures.
癫痫是复杂控制系统不稳定的典型表现。我们之前已经确定了猫丘脑皮质运动系统中与癫痫样活动相关且受常见抗惊厥药控制的参数。本研究关注小脑刺激对这些参数的控制，这可能会促进运动系统内的稳定性。在计算机控制下，刺激被施加到腹外侧丘脑和小脑皮质，并对从感觉运动皮质获得的诱发反应进行多通道记录。皮质诱发反应被绘制成兴奋性曲线（平均反应幅度作为脉冲间隔的函数）或一组阈值曲线（平均反应幅度作为不同固定间隔下刺激幅度的函数）。本研究表明，小脑硬膜外刺激可降低兴奋性曲线的高度和持续时间，同时提高反应阈值并降低阈值曲线的饱和水平。这些参数变化的程度和方向取决于小脑刺激的频率、极性和幅度，参数变化量超过了单药剂量抗惊厥药所达到的效果。这些数据表明，控制丘脑皮质运动系统中与兴奋性和阈值相关的参数可能是小脑刺激实现临床癫痫控制的方式。
