Possible Molecular and Cellular Mechanism Underlying Ectopic Mossy Fiber Guidance
BDNF has been shown to be necessary and sufficient to promote hyperactivity-induced mossy fiber sprouting in hippocampal slice cultures .
CA3 pyramidal cells received excitatory synaptic inputs mainly from two sources: collateral axons from other CA3 pyramidal cells synapse on the medial apical and basal dendrites (CA3-CA3 synapse), and mossy fiber axons of dentate granule cells on the proximal, basal, and apical dendrite (mf-CA3 synapse).
Giant spontaneous EPSCs at the hippocampal mossy fiber to CA3 pyramidal cell are monoquantal [19-22] and in our experimental condition should correspond to the second Gaussian peak, at about 120 pA.
In the sclerotic hippocampus, mossy fibers
were also found to form asymmetrical (presumably excitatory) synapses on granule cell somata ((e), arrowhead).
Enhancement of hippocampal mossy fiber activity in zinc deficiency and its influence on behavior.
All hippocampal mossy fibers contain zinc in presynaptic vesicles, and [Zn.sup.2+] is co-released with glutamate (Frederickson, 1989; Frederickson and Danscher, 1990).
Furthermore, it remains unclear if decreased DG activity leads to less glutamatergic input to CA3 from the DG through mossy fibers. Although mossy fibers from the DG to CA3 are glutamatergic and come into direct contact with CA3 pyramidal neurons, many mossy fiber synapses are connected to interneurons in CA3 that provide GABAergic inhibitory input to CA3 pyramidal cells.
Barrionuevo, "The multifarious hippocampal mossy fiber pathway: a review," Neuroscience, vol.
cAMP contributes to mossy fiber LTP by initiating both a covalently mediated early phase and macromolecular synthesis-dependent late phase.
Hippocampal mossy fiber LTP is independent of postsynaptic calcium.
Nistico et al., "A role for [Ca.sup.2+] stores in kainate receptor-dependent synaptic facilitation and LTP at mossy fiber synapses in the hippocampus," Neuron, vol.
Cotman, "Long-term potentiation of guinea pig mossy fiber responses is not blocked by N-methyl D-aspartate antagonists," Neuroscience Letters, vol.
Noda, "Visual mossy fiber inputs to the flocculus of the monkey, " Annals of the New York Academy of Sciences, vol.
As the majority of the mossy fibers (MFs) reaching the horizontal zone of the flocculus originated in the contralateral vestibular , the prepositus , the incertus nuclei , and the paramedian tract region , the section of the vestibular commissure in the cat resulted in the absence of VOR adaptation , and that inspite of that fact, the right and left flocculus were preserved.