Baba H, Wada J A
Division of Neurosciences, University of British Columbia, Vancouver, Canada.
Electroencephalogr Clin Neurophysiol. 1987 Dec;67(6):556-63. doi: 10.1016/0013-4694(87)90058-7.
Transcallosal response (TCR) and its recovery cycle were studied in the chronic photosensitive baboon, Papio papio. Bipolar premotor intracortical stimulation evoked early positive (P1) and negative (N1) sequences followed by late small positivity (P2) and large negativity (N2) in the contralateral homotopic site. The sequential pattern of P1 and N1 was similar to that previously described in acute preparations. The recovery cycle as measured by means of paired stimuli with varying inter-stimulus intervals (ISI) showed a marked supernormality of P1 and N1 at an ISI of 15-200 msec with maximal facilitation up to 250-300% of the conditioning response at an ISI of 30-50 msec. Pentobarbital (10 mg/kg) suppressed this supernormality without causing a constant TCR amplitude change. In contrast, a significant increase in both the TCR amplitude and the supernormality of the recovery cycle was observed with a subconvulsive dose (3 mg/kg) of Megimide, a presumed antagonist of pentobarbital. Our results suggest that (a) the recovery cycle is a more sensitive measure than amplitude for assessing the effect of neurotropic drugs on TCR, and (b) the P1, N1 amplitudes and the supernormality may represent different neuronal processes involved in the TCR.
在慢性光敏狒狒（豚尾狒狒）中研究了胼胝体反应（TCR）及其恢复周期。双极运动前皮质内刺激在对侧同位点诱发了早期正波（P1）和负波（N1）序列，随后是晚期小正波（P2）和大负波（N2）。P1和N1的序列模式与先前在急性实验准备中描述的相似。通过具有不同刺激间隔（ISI）的成对刺激测量的恢复周期显示，在ISI为15 - 200毫秒时，P1和N1有明显的超常期，在ISI为30 - 50毫秒时，最大易化可达条件反应的250 - 300%。戊巴比妥（10毫克/千克）抑制了这种超常期，但没有导致TCR振幅持续变化。相反，使用戊巴比妥的假定拮抗剂美解眠的亚惊厥剂量（3毫克/千克）时，观察到TCR振幅和恢复周期超常期均显著增加。我们的结果表明：（a）恢复周期是比振幅更敏感的指标，用于评估神经营养药物对TCR的影响；（b）P1、N1振幅和超常期可能代表了TCR中不同的神经元过程。
