Learning and Memory in Barnes Maze Don’t Lead to Synaptic Potentiation in Freely Moving Rat Hippocampus

Introduction: Synaptic plasticity has been suggested as the primary physiological mechanism underlying memory formation. Many experimental approaches have been used to investigate whether the mechanisms underlying Long-Term Potentiation (LTP) are activated during learning. Nevertheless, little evidence states that hippocampal-dependent learning triggers synaptic plasticity. In this study, we investigated if learning and memory in the Barnes maze test are accompanied by the occurrence of LTP in Schaffer collateral to CA1 synapses in freely moving rats. Methods: The rats were implanted with a recording electrode in stratum radiatum and stimulating electrodes in Schaffer collaterals of the CA1 region in the dorsal hippocampus of the right hemisphere. Following the recovery period of at least 10 days, field potentials were recorded in freely moving animals before and after training them in Barnes maze as a hippocampal-dependent spatial learning and memory test. The slope of extracellular field Excitatory Postsynaptic Potentials (fEPSPs) was measured before and after the Barnes maze test. Results: The results showed that the fEPSP slope did not change after learning and memory in the Barnes maze test, and this spatial learning did not result in a change in synaptic potentiation in the CA1 region of the hippocampus. Conclusion: Spatial learning and memory in the Barnes maze test are not accompanied by LTP induction in Schaffer collateral-CA1 synapses.