Bramham C R, Srebro B
Department of Physiology, University of Bergen, Norway.
Brain Res. 1989 Jul 24;493(1):74-86. doi: 10.1016/0006-8993(89)91001-9.
The possible influence of the sleep-waking cycle on evoked neurotransmission and on the induction of long-term potentiation (LTP) and depression (LTD) was studied in the perforant path-granule cell system. Freely moving rats received a high-frequency stimulus train (8 bursts at 400 Hz) during slow-wave sleep (SWS), rapid eye movement (REM) sleep, and a still-alert (SAL) behavioral state. Trains applied during SAL and REM reliably elicited LTP of the excitatory postsynaptic potential (EPSP) slope, population spike height, and spike onset latency. Granule cell excitability was also enhanced, as indicated by a leftward shift of the EPSP-population spike (E-S) relation. In contrast, tetanization in SWS rarely produced 'classical' LTP and often failed to elicit any lasting change in field potentials. Furthermore, the following types of E-S change occurred almost exclusively after tetanization in SWS: (1) LTP of the EPSP accompanied by depression of the population spike, and (2) E-S potentiation without a change in EPSP. When LTP occurred, however, its magnitude was independent of the animal's behavioral state at the time of the train. In agreement with previous reports, the efficacy of low-frequency neurotransmission varied with behavioral state. A modulation index (MI) was introduced to quantify the difference between field potentials evoked in SAL and SWS. Interestingly, both the occurrence and magnitude of LTP were related to the strength of the MI, as determined in each rat before the train. After trains, the state-dependent modulation of transmission was maintained and was superimposed on LTP and LTD. The results suggest that synaptic plasticity is dynamically modulated during the sleep-wakefulness cycle.
在穿通通路-颗粒细胞系统中，研究了睡眠-觉醒周期对诱发神经传递以及长时程增强（LTP）和长时程抑制（LTD）诱导的可能影响。自由活动的大鼠在慢波睡眠（SWS）、快速眼动（REM）睡眠和静息警觉（SAL）行为状态下接受高频刺激串（400Hz，8个脉冲）。在SAL和REM期间施加的刺激串可靠地诱发了兴奋性突触后电位（EPSP）斜率、群体峰电位高度和峰电位起始潜伏期的LTP。颗粒细胞兴奋性也增强，表现为EPSP-群体峰电位（E-S）关系向左移位。相比之下，在SWS中进行强直刺激很少产生“经典”LTP，并且常常未能引起场电位的任何持久变化。此外，以下类型的E-S变化几乎仅在SWS中强直刺激后出现：（1）EPSP的LTP伴随着群体峰电位的抑制，以及（2）E-S增强而EPSP无变化。然而，当发生LTP时，其幅度与刺激串施加时动物的行为状态无关。与先前的报道一致，低频神经传递的功效随行为状态而变化。引入调制指数（MI）以量化在SAL和SWS中诱发的场电位之间的差异。有趣的是，LTP的发生和幅度均与MI的强度相关，该强度在每只大鼠刺激串施加前确定。刺激串后，传递的状态依赖性调制得以维持，并叠加在LTP和LTD上。结果表明，突触可塑性在睡眠-觉醒周期中受到动态调制。
