Long-term potentiation (LTP) at the mossy fiber-->CA3 pyramidal cell synapse in the hippocampus is an NMDA-independent form of LTP that requires cAMP-dependent protein kinase (PKA) activity and can be induced by forskolin, a general activator of adenylyl cyclases. Presynaptic Ca2+ influx and elevated cAMP may be obligatory for mossy fiber LTP. Because the Ca2+-stimulated type 1 adenylyl cyclase...

The granular layer of the cerebellum has a disproportionately large number of excitatory (granule cells) versus inhibitory neurons (Golgi cells). Its synaptic organization is also unique with a dense reciprocal innervation between granule and Golgi cells but without synaptic contacts among the neurons of either population. Physiological recordings of granule or Golgi cell activity are scarce, a...

cAMP and the cAMP-dependent protein kinase (PKA) are required in the mossy fiber pathway for both the early and the late phase of long-term potentiation (LTP). Since the CA3 region, which is the target of the mossy fibers, receives extensive noradrenergic innervation, we examined the role of beta-adrenergic receptors in mossy fiber LTP. We found that we could induce an early phase of LTP by pai...

We have used a number of approaches to address a possible role of metabotropic glutamate receptors (mGluRs) in mossy fiber long-term potentiation (LTP) in the hippocampus. We have used two types of mutant mice--one lacking the mGluR1 subtype of receptor and one lacking the gamma isoform of protein kinase C. In neither type of mouse did we find any alteration in the magnitude of mossy fiber LTP....

The mossy fiber to CA3 pyramidal neuron synapse in the hippocampus displays an atypical form of NMDA receptor-independent long-term potentiation (LTP). Plasticity at this synapse is expressed in the presynaptic terminal as an elevated probability of neurotransmitter release. However, evidence indicates that postsynaptic mechanisms and trans-synaptic signaling through an association between post...

Behavioral and computational studies predict that synaptic plasticity of excitatory mossy fiber inputs to cerebellar nuclear neurons is required for associative learning, but standard tetanization protocols fail to potentiate nuclear cell EPSCs in mouse cerebellar slices. Nuclear neurons fire action potentials spontaneously unless strongly inhibited by Purkinje neurons, raising the possibility ...

Dentate granule cells process information from the enthorinal cortex en route to the hippocampus proper. These neurons have a very negative resting membrane potential and are relatively silent in the slice preparation. They are also subject to strong feed-forward inhibition. Their unmyelinated axon or mossy fiber ramifies extensively in the hilus and projects to stratum lucidum where it makes g...

The spatiotemporal activities of astrocyte Ca²⁺ signaling in mature neuronal circuits remain unclear. We used genetically encoded Ca²⁺ and glutamate indicators as well as pharmacogenetic and electrical control of neurotransmitter release to explore astrocyte activity in the hippocampal mossy fiber pathway. Our data revealed numerous localized, spontaneous Ca²⁺ signals in astrocyte branches and ...

In the pilocarpine model of temporal lobe epilepsy, mossy fibers coexpress the inhibitory transmitter neuropeptide Y (NPY) with glutamate. The effects of endogenous and applied NPY on recurrent mossy fiber synaptic transmission were investigated with the use of whole-cell voltage-clamp and field recordings in rat hippocampal slices. Applied NPY reversibly inhibited synaptic transmission at recu...