An important pool of chelatable zinc is present in the synaptic vesicles of mossy fiber terminals from hippocampal CA3 area, being zinc released following single or repetitive electrical stimulation. Previous studies have suggested different synaptic roles for released mossy fiber zinc, including the inhibition of presynaptic calcium and of postsynaptic N-methyl-D-aspartate (NMDA) and gamma ami...

Mossy fiber sprouting (MFS), a common feature of human temporal lobe epilepsy and many epilepsy animal models, contributes to hippocampal hyperexcitability. The molecular events responsible for MFS are not well understood, although the growth-associated protein GAP-43 has been implicated in rats. Here, we focus on the hyaluronan receptor CD44, which is involved in routing of retinal axons durin...

Using a genetic approach, we assessed the effects of mutations in protein kinase A (PKA) on long-term potentiation (LTP) in the mossy fiber pathway and its relationship to spatial and contextual learning. Ablation by gene targeting of the C beta 1 or the RI beta isoform of PKA produces a selective defect in mossy fiber LTP, providing genetic evidence for the role of these isoforms in the mossy ...

The hippocampus contains one very strong recurrent excitatory network formed by associational connections between CA3 pyramidal cells and another that depends largely on a disynaptic excitatory pathway between dentate granule cells. The recurrent excitatory network in CA3 has long been considered a possible location of autoassociative memory storage, whereas changes in the level and arrangement...

The function of neuronal networks relies on selective assembly of synaptic connections during development. We examined how synaptic specificity emerges in the pontocerebellar projection. Analysis of axon-target interactions with correlated light-electron microscopy revealed that developing pontine mossy fibers elaborate extensive cell-cell contacts and synaptic connections with Purkinje cells, ...

One million mossy fibers in the rat provide individually sparse but functionally important synaptic connections between the dentate gyrus and hippocampus. Although the majority of mossy fiber targets are GABAergic cells, the functional organization of the feedforward GABAergic machinery modulating the interactions of granule cells and CA3 pyramidal cells are not yet understood. We used mossy fi...