The Recurrent Mossy Fiber Pathway of the Epileptic Brain

  title={The Recurrent Mossy Fiber Pathway of the Epileptic Brain},
  author={J. Victor Nadler},
  journal={Neurochemical Research},
  • J. Nadler
  • Published 1 November 2003
  • Biology
  • Neurochemical Research
The dentate gyrus is believed to play a key role in the pathogenesis of temporal lobe epilepsy. In normal brain the dentate granule cells serve as a high-resistance gate or filter, inhibiting the propagation of seizures from the entorhinal cortex to the hippocampus. The filtering function of the dentate gyrus depends in part on the near absence of monosynaptic connections among granule cells. In humans with temporal lobe epilepsy and in animal models of temporal lobe epilepsy, dentate granule… 

Recurrent Mossy Fibers Establish Aberrant Kainate Receptor-Operated Synapses on Granule Cells from Epileptic Rats

It is reported that KARs are involved in ongoing glutamatergic transmission in granule cells from chronic epileptic but not control animals, and KAR-mediated EPSCKAs are selectively generated by recurrent mossy fiber inputs and have a slower kinetics than EPSCAMPA.

Neuropeptide Y in the recurrent mossy fiber pathway

Plasticity of Dentate Granule Cell Mossy Fiber Synapses: A Putative Mechanism of Limbic Epileptogenesis

This chapter reviews evidence implicating the granule cells as gatekeepers in a normal brain, as well as, evidence of compromise of the gatekeeper function in an epilepsy model, and proposes that plasticity of dentate granule cell mossy fiber synapses is a putative mechanism of limbic epileptogenesis.

Enhanced Synaptic Connectivity in the Dentate Gyrus during Epileptiform Activity: Network Simulation

Computer modelling of the dentate gyrus circuitry and the corresponding structural changes has been used to understand how abnormal mossy fibre sprouting can subserve seizure generation observed in experimental models when epileptogenesis is induced by status epilepticus and suggest that there is a joint action of the compensation theory and Hebbian rules during the inflammatory process that accompanies the status epileptus.

Spontaneous Release of Neuropeptide Y Tonically Inhibits Recurrent Mossy Fiber Synaptic Transmission in Epileptic Brain

Tonic release of NPY accounts at least partially for the low probability of glutamate release from recurrent mossy fiber terminals, impedes the ability of these fibers to synchronize granule cell discharge, and may protect the hippocampus from seizures that involve the entorhinal cortex.

Status Epilepticus Induced Spontaneous Dentate Gyrus Spikes: In Vivo Current Source Density Analysis

Dentate spikes are investigated following status epilepticus to suggest that following SE there is an increase in DS activity, potentially arising from hyperexcitability along the hippocampal-entorhinal pathway or within the dentate gyrus itself.



Short-Term Frequency-Dependent Plasticity at Recurrent Mossy Fiber Synapses of the Epileptic Brain

The results suggest that the recurrent mossy fiber pathway may be functionally silent during baseline asynchronous granule cell activity in vivo attributable, in part, to progressive transmission failure.

Recurrent mossy fiber pathway in rat dentate gyrus: synaptic currents evoked in presence and absence of seizure-induced growth.

The hypothesis that recurrent mossy fiber growth and synapse formation increases the excitatory drive to dentate granule cells and thus facilitates repetitive synchronous discharge is supported.

Modest increase in extracellular potassium unmasks effect of recurrent mossy fiber growth.

Results indicate that even modest changes in [K(+)](o) dramatically affect granule cell epileptiform activity supported by the recurrent mossy fiber pathway, and that block of GABA(A) receptor-mediated inhibition is less efficacious and frequency facilitation may not be a significant factor.

Mossy fiber-granule cell synapses in the normal and epileptic rat dentate gyrus studied with minimal laser photostimulation.

The strong similarity between responses from the status epilepticus and control groups suggests that they resulted from activation of a similar synaptic population, and new synapses appear to operate very similarly to preexisting mossy fiber-granule cell synapses.

Mossy fiber synaptic reorganization in the epileptic human temporal lobe

The results are morphological evidence of mossy Fiber synaptic reorganization in the temporal lobe of epileptic humans, and suggest the intriguing possibility that mossy fiber sprouting and synaptic reorganizing induced by repeated partial complex seizures may play a role in human epilepsy.

NMDA receptor-dependent plasticity of granule cell spiking in the dentate gyrus of normal and epileptic rats.

NMDA receptor-dependent plasticity of granule cell spike generation, which can be distinguished from LTP and induces long-term susceptibility to epileptic burst discharge under conditions of reduced inhibition, could modify information processing in the hippocampus and promote epileptic synchronization by increasing excitatory input into CA3.

Lack of effect of mossy fiber-released zinc on granule cell GABA(A) receptors in the pilocarpine model of epilepsy.

The results suggest that zinc released from the recurrent mossy fiber pathway did not reach a concentration at postsynaptic GABA(A) receptors sufficient to inhibit agonist-evoked activation.

Status epilepticus‐induced hilar basal dendrites on rodent granule cells contribute to recurrent excitatory circuitry

The results indicate that HBDs are present in the pilocarpine model of temporal lobe epilepsy, confirm the presence of H BDs in the kainate model, and show that Hbds are postsynaptic to mossy fibers.

Decreased hippocampal inhibition and a selective loss of interneurons in experimental epilepsy.

Results suggest that the seizure-induced loss of a basket cell-activating system, rather than a loss of inhibitory basket cells themselves, may cause disinhibition and thereby play a role in the pathophysiology and pathology of the epileptic state.