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.