Mossy fiber appearance

PKA-dependent long-term potentiation and depression was initially discovered in the mossy-fiber synapses of the hippocampus, and later demonstrated in parallel fiber synapses of the cerebellum and corticothalamic synapses of the forebrain (Malenka and Siegelbaum, 2001). This widespread form of plasticity does not involve changes in Ca2+-influx, but operates via a direct increase or decrease, respectively, of the amount of vesicle exocytosis that can be triggered by a given Ca2+-signal. Interestingly, this form of plasticity appears to depend on the interaction... 

Summarizing it appears that the cellular and regional distribution of muscarine receptors in the cerebellum is different between different species. Golgi cells and subpopulations of mossy fibers seem to express muscarine receptors most constantly. An interesting aspect about the presence of muscarine receptors in parallel fibers in rat and rabbit, is that the lobular distribution of m2-containing parallel fibers, is the same as that of ChAT-positive mossy fiber rosettes (see above). This raises the possibility that muscarine m2 receptor are specifically expressed by those granule cells that are innervated by cholinergic mossy fibers. If this proves to be true, this would imply that there... 

The development of the granule cell-pyramidal cell pathway appears to be particularly vulnerable to altered thyroid hormone levels during the postnatal period. For example. Rami et al. (1986b) reported that the dendritic arborizations of both of these cell types are hypoplastic in hypothyroid animals, and that the severity of the deficit in pyramidal cell dendrites is found in that population of cells which receive input from granule cell axons, the mossy fibers. This same population of cells is the most responsive to replacement therapy with thyroxine, according to these authors. 

---