Synapse
-
Fimbrial control of bidirectional synaptic plasticity of medial perforant path-dentate transmission.
Lesions of the fimbria-fornix (FF) tract cause profound impairments of cognitive ability in animals. Our previous study showed that spatial performance correlates with long-term potentiation (LTP) of the dentate gyrus (DG), but not of the CA1 region, in rats with bilateral FF lesions, suggesting that FF lesions selectively inhibited LTP in the DG. The cortical input to the DG is anatomically and physiologically divided into two types of afferents, i.e., the medial perforant path (MPP) and the lateral perforant path (LPP), which show distinct synaptic properties. ⋯ The low-frequency burst stimulation could not induce LTD at LPP-DG synapses in either intact or FF-lesioned rats. These results suggest that the FF pathway selectively supports the mechanisms of bidirectional synaptic plasticity at MPP-DG synapses. This study provides new insights into external control of information processing in the hippocampus.