Bramham C R, Srebro B
Brain Res. 1987 Mar 3;405(1):100-7. doi: 10.1016/0006-8993(87)90994-2.
We investigated the possible importance of stimulus train frequency for the induction and magnitude of long-term synaptic plasticity in the perforant path-granule cell pathway. Under the same experimental conditions, low- (15 Hz) or high-frequency (400 Hz) stimulation could elicit a profound long-term depression (LTD), or typical long-term potentiation (LTP), of the population spike amplitude, excitatory postsynaptic potential (EPSP) amplitude and spike onset latency. In addition, changes in the relationship between the EPSP and population spike amplitude indicated that granule cell excitability was enhanced during LTP and reduced during LTD. LTD occurred primarily after low-frequency stimulation (5 of 6 cases), and was always accompanied by striking changes in the EEG, most notably a biphasic slow potential. While the EEG changes were confined to the first 5 min after the tetanus, LTD lasted from 1 to 4 h. The nature of the EEG events is still unclear, it is suggested that they may represent a spreading depression-like episode. Finally, we found that LTP evoked by high-frequency stimulation was larger and generally reached peak magnitude faster than when it followed low-frequency stimulation. A possible mechanism and role for hippocampal LTD is proposed.
我们研究了刺激串频率对穿通通路-颗粒细胞通路中长时程突触可塑性的诱导及幅度的潜在重要性。在相同实验条件下，低频（15Hz）或高频（400Hz）刺激均可引发群体峰电位幅度、兴奋性突触后电位（EPSP）幅度及峰电位起始潜伏期的深度长时程抑制（LTD）或典型的长时程增强（LTP）。此外，EPSP与群体峰电位幅度之间关系的变化表明，在LTP期间颗粒细胞兴奋性增强，而在LTD期间降低。LTD主要发生在低频刺激后（6例中有5例），并且总是伴随着脑电图（EEG）的显著变化，最明显的是双相慢电位。虽然EEG变化局限于强直刺激后的最初5分钟，但LTD持续1至4小时。EEG事件的性质仍不清楚，有人认为它们可能代表类似扩散性抑制的发作。最后，我们发现高频刺激诱发的LTP比低频刺激后诱发的LTP幅度更大，且通常更快达到峰值幅度。本文提出了海马LTD的一种可能机制及作用。
