大鼠视皮层场电位在发育过程中及LTP形成前后的变化

目的　探讨视皮层发育过程中场电位的变化规律及长时程增强 (LTP)形成前后场电位的变化规律。方法　应用视皮层脑片电生理技术 ,在大鼠视皮层脑片Ⅳ层刺激而在Ⅱ /Ⅲ层记录场电位 ,比较出生后第 2、3、5周场电位的变化。在第 3周龄的大鼠脑片中诱导LTP ,场电位稳定后以一组强直刺激诱导LTP ,并比较强直刺激前后场电位幅值、潜伏期以及斜率的变化。结果　第 3周诱导场电位的阈刺激强度较第 2及第 5周低。在第 3周龄大鼠的实验中 ,强直刺激后斜率增大与幅值升高呈正相关 ,潜伏期的缩短与斜率和幅值变化率的差值呈正相关。结论　发育过程中场电位的变化可反映皮层的发育。斜率综合了幅度及潜伏期的变化 ,是判定LTP的一个较好指标

Changes of field potentials during development and after long-term potentiation in developing rat visual cortical slices

Objective To study the changes of field potentials (FPs) during development and after long-term potentiation (LTP) induction in rat visual cortical slices. Methods Field potentials recorded from layer Ⅱ/Ⅲ induced by layer Ⅳ in the rat visual cortical slices were examined. The developing changes of FPs from postnatal days 8-13,15-21 and 29-35 were observed. Amplitudes, peak latencies and slopes of FPs before and after LTP induction were compared. Results Field potentials changed with the development, and the stimulating threshold at p15-21 was lower than that of the other two groups. The increase of FP amplitude was positively correlated with increase of its slope. The shortening of FP latency was positively correlated with the difference between changes of slope and amplitude. Conclusion Developing changes of field potentials reflect the development of visual cortex. The changes of FP slope follow the changes of its amplitude and latency, and thereby the slope is a proper parameter used as an index to evaluate LTP in visual cortex.