乳头体对海马齿状回习得性长时程突触增强的影响

用高频电脉冲刺激大鼠乳头体（ＭＢ），可一过性抑制由刺激穿通纤维（ＰＰ）诱发的海马齿状回（ＤＧ）群体锋电位（ＰＳ）。训练作业前先刺激ＭＢ，导致ＤＧ的习得性长时程突触增强（ＬＤＬＴＰ）的形成显著延缓，相应地延缓了条件性饮水反应的建立。电刺激ＭＢ对ＰＰ─ＤＧＰＳ的这种抑制作用在训练所产生的ＰＳ增大达最高水平时显著减弱，刺激ＭＢ对ＬＤＬＴＰ的保持及相应地对条件反应的巩固没有明显影响。结果表明ＭＢ对ＤＧＬＤＬＴＰ的形成有抑制性调制作用。

EFFECT OF MAMMILLARY BODY ON LEARNING-DEPENDENT LONG-TERM POTENTIATION IN HIPPOCAMPAL DENTATE GYRUS

Population spikes(PS) were recorded from dentate gyrus(DG)of freely moving rats following stimulation of the perforant path. The rats were trained to perform conditioned drinking behavior.(1)High-frequency stimulation(HFS) of the mammillary body(MB) could elicit a temporary inhibition of PS in DG.(2)Animals were treated with HFS of MB before daily trai ning session,the development of learning-dependent long-term potentiation(LDLTP)was depressed significantly, and the establishment of conditioned response was suppressed parallelly,(3)The inhibitory effect of HFS of MB on PS in DG was weakened significantly as the enhancement of PS amplitude reached the maximal level.(4)HFS of MB had no clear effect on the retention of LDLTP and the consolidation of conditioned response.The results suggested that MB might exert an inhibitory modulation on the development of LDLTP in DG.