大鼠丘脑侧后核到初级视皮层突触传递的短时程可塑性

大鼠丘脑侧后核(lateral posterior thalamic nucleus,LP nucleus)到初级视皮层的突触连接是膝体外视觉通路的重要组成部分.运用场电位记录和电泳的方法在位研究了该视觉回路突触传递的短时程可塑性.结果表明，无论是运用双脉冲刺激还是串刺激都能观察到明显的短时程抑制特性.电泳荷包牡丹碱(bicuculline)和2-hydroxy-saclofen使该抑制作用减弱，电泳钙离子使抑制加强，电泳APV对抑制作用没有明显影响.所以突触前递质释放水平的改变，和γ-氨基丁酸(GABA)能受体（尤其是GABA_B受体）的活动都会影响该回路突触传递的短时程可塑性，而N-甲基-D-天冬氨酸(NMDA)受体则几乎没有作用.该回路很强的短时程抑制特性可能与LP核在视觉注意中的作用有关.

The Short-term Plasticity of Synaptic Transmission From Rat Lateral Posterior Thalamic Nucleus to Primary Visual Cortex

The synaptic connection from rat lateral posterior thalamic nucleus to primary visual cortex is an important part of extrageniculate visual pathway. The short-term plasticity of this synaptic transmission is investigated in vivo by using field potential recording and iontophoresis methods. The field potentials were depressed rigorously by either paired-pulse stimulation or repetitive stimulation at different frequency (10, 20, 50 Hz). Iontophoresis of bicuculline and 2-hydroxy-saclofen decreased the depression degree, while iontophoresis of Ca²⁺ increased the depression degree. Therefore, the short-term plasticity of synaptic transmission in this pathway is affected by many factors, such as: changing the transmitter release level at pre-synaptic terminal and activity of GABAergic receptors. However, when applying APV, the selective antagonist of NMDA receptors, no any obvious change in short-term synaptic plasticity was obtained. The rigorous short-term plasticity in this visual pathway may play a role in the visual attention function, which is related to the lateral posterior thalamic nucleus.