Figure 1

LTP activates hippocampal precursors in vitro. To investigate whether LTP enhances proliferation of neural precursors, mice were assayed for neurosphere formation 2 days after stimulation (n=11, 4, 6 and 4, for the LTP(+), CPP, LFS and LTP(−) groups, respectively). Under normal K⁺ conditions, only the LTP(+) group revealed a significant increase in neurosphere number from the stimulated hemisphere relative to control hemisphere (P=0.002, Wilcoxon matched-pairs signed rank test). Furthermore, a significantly greater number of neurospheres were generated from stimulated hippocampi of the LTP(+) group compared with the simulated hippocampi of the CPP group (P<0.0001, Student's t-test with Welch's correction) and LTP(−) group (P=0.0016, Student's t-test with Welch's correction). When CPP was administered to block the NMDA receptor, neurosphere formation was significantly reduced compared with the LTP(+) group (low K⁺: P<0.0001, high K⁺: P=0.0006, Student's t-test with Welch's correction) and LTP(−) group (low K⁺: P=0.0018, high K⁺: P=0.0078, Student's t-test with Welch's correction). Error bars indicate s.e.m., low: low K⁺, high: high K⁺. ^**P<0.01, ^***P<0.001. Abbreviations: CPP, 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid; LTP, long-term potentiation; NMDA, N-Methyl-D-aspartic acid.