Effect of extremely low-frequency electromagnetic field (50 Hz, 5mT) on memory consolidation and retrieval in male rats

Abstract

BACKGROUND AND OBJECTIVE: Power lines and household electrical appliances (TV, computer, and hairdryer) emit extremely low-frequency magnetic field (ELF-MF) that can be damaging. As the exposure of these MF is increasing now days and important effect of MF on memory formation, in this study effects of these fields on memory consolidation and retrieval in male rats were examined. METHODS: In this experimental study, 90 male Wistar rats were divided into nine groups. Control group was trained in shuttle box (passive avoidance box). Sham group was put in turn off MF immediately after training for 4 hrs. Four test groups of memory consolidation after training were exposed on MF for 1, 4, 6 and 8 hrs respectively. The rats were exposed on MF (50 Hz, 5mT). Three test groups of memory retrieval after testing, were exposed on MF (4 hrs) for 3, 4 and 5 days respectively and were tested again 24 hrs after the last exposure. In all of groups, the time of entrance from light to dark area was measured in shuttle box as" retention latency and compared. FINDINGS: In 4 test groups of memory consolidation, between first group that was exposed on MF for hr (485± 76s), and control group (583±17s) difference was not significant (p<0.05) while in other groups that were exposed on MF for 4, 6, 8 hrs (303±17, 294±87, 191±72s) difference was significant (p<0.05). Between sham group (541± 58) and test group that was exposed on MF for 4 hrs (303±17) difference was significant (p<0.05). The results of 3 test groups of memory retrieval showed that there was not any significant difference between before (572±37, 580±54.8 and 585±51.4) and after (563±42, 545.2±54.8 and 548.6±51.4) exposing for 3, 4 and 5 days. CONCLUSION: Acute exposure on ELF-MF can acutely prevent from memory consolidation but had no effect on memory retrieval.