GABAergic innervation of the rat fascia dentata: A novel type of interneuron in the granule cell layer with extensive axonal arborization in the molecular layer

1993 ◽  
Vol 334 (3) ◽  
pp. 385-396 ◽  
Author(s):  
Eduardo Soriano ◽  
Michael Frotscher
1986 ◽  
Vol 55 (4) ◽  
pp. 739-750 ◽  
Author(s):  
E. J. Green ◽  
W. T. Greenough

Pre- and postsynaptic responses to activation of medial perforant path (MPP) axons were examined in hippocampal slices taken from rats reared for 3-4 wk in relatively complex (EC) or individual cage (IC) environments. Three types of extracellular field potentials were recorded in the infrapyramidal blade of the dentate gyrus: 1) granule cell population spikes (PSs), which reflect the number and synchrony of discharging granule cells (2), 2) population excitatory postsynaptic potentials (EPSPs), which reflect the amount of excitatory synaptic current flow into dendrites (28), and 3) presynaptic fiber volleys (FVs), which reflect the number of activated axons (28). Stimulation of the MPP evoked significantly larger PSs in slices taken from EC rats. There was no significant effect of rearing environment on PS/EPSP relationships. The slopes of EPSPs recorded at the site of synaptic activation in the dentate molecular layer and at the major current source in the dentate granule cell layer were significantly greater in slices taken from EC rats. The presynaptic FV was recorded at the site of synaptic activation in the molecular layer. FV amplitude did not differ significantly as a function of rearing environment. To examine possible differences in tissue impedance, granule cells were activated by stimulating granule cell axons in the dentate hilus and recording the antidromic PS in the granule cell layer. Antidromic PS amplitude was not significantly affected by rearing environment. The relative permanence of the experience-dependent alterations in synaptic transmission was assessed by comparing slices taken from rats that had been reared for 4 wk in complex environments followed by 3-4 wk in individual cages with those from rats reared for 7-8 wk in individual cages. There were no significant differences in MPP synaptic transmission between these groups of animals. The results suggest that experience in a relatively complex environment is associated with greater MPP synaptic transmission arising from an increased synaptic input to granule cells; the greater MPP synaptic transmission associated with behavioral experience can occur independent of behavioral state, influences from extrahippocampal brain regions and intrahippocampal inhibitory activity; and the experience-dependent synaptic alterations in the dentate gyrus are transient, in contrast to experience-dependent morphological alterations described in occipital cortex. The possible relationship of these alterations to the phenomenon of long-term enhancement is discussed.


1984 ◽  
Vol 60 (4) ◽  
pp. 845-847 ◽  
Author(s):  
Uros Roessmann ◽  
Thamnook Wongmongkolrit

✓ Dysplastic gangliocytoma of the cerebellum is reported in a newborn. It is characterized by large ganglion cells in the molecular layer and premature attenuation of the external granule-cell layer. The internal granule-cell layer appears rarefied but otherwise normally organized. It appears that in this disease the migrating granule cells mature too early and become arrested in the molecular layer, because of their abnormal forms, while others continue to migrate and grow in size in their normal location in the inner granule-cell layer.


1990 ◽  
Vol 110 (4) ◽  
pp. 1275-1283 ◽  
Author(s):  
K S O'Shea ◽  
J S Rheinheimer ◽  
V M Dixit

The patterns of deposition of thrombospondin (TSP), a trimeric extracellular matrix glycoprotein, were determined during the initial establishment of the external granule cell layer and the subsequent inward migration of granule cells forming the molecular and (internal) granule cell layers. The early homogeneous deposition of TSP became restricted to the rhombic lip in the region of granule cell exit from the neuroepithelium, and was present between migrating granule cells. During the later inward migration of granule cells, little TSP was associated with dividing granule cells; it was enriched in premigratory granule cells. With the cessation of migration, TSP was lost except in association with fasciculating axons in the molecular layer where staining persisted briefly. At the EM level, TSP was associated with the leading process of granule cells as they associated with Bergmann glial cells and migrated through the molecular layer. TSP was present within granule cell axons; Purkinje cells and their dendrites, as well as Bergmann glial fibers and endfeet were negative for TSP. When anti-TSP antibodies were added to explant cultures of cerebellar cortex during active granule cell migration, a dose-dependent inhibition of migration was observed. In control cultures, granule cells migrated into the (internal) granule cell layer, while granule cells exposed to anti-TSP antibodies were arrested within the external granule cell layer. These results suggest that TSP plays an important role in the histogenesis of the cerebellar cortex by influencing granule cell migration.


2017 ◽  
Vol 89 (1) ◽  
pp. 15-32 ◽  
Author(s):  
Kosuke Imura ◽  
Naoyuki Yamamoto ◽  
Masami Yoshimoto ◽  
Masato Endo ◽  
Kengo Funakoshi ◽  
...  

The caudal part of the corpus cerebelli of Nile tilapia can be divided into dorsal and ventral regions. The granule cell layer of the dorsal (dGL) and ventral (vGL) regions of the caudal corpus cerebelli is known to receive indirect inputs from the telencephalon relayed by the nucleus paracommissuralis. The descending pathways are topographically organized, and the dGL and vGL receive inputs from different dorsal telencephalic parts. The caudal corpus cerebelli, in turn, projects extracerebellar efferents. However, it remains unknown how the descending telencephalic inputs are processed within the cerebellum. Therefore, the present study investigated intrinsic connections of the caudal corpus cerebelli by injecting neural tracers into the molecular layer of dorsal and ventral regions. Injections of tracers into the ventral molecular layer resulted in labeled cells in the vGL and the ganglionic layer of the ventral corpus. The axonal trajectories from labeled cells in the ganglionic layer were analyzed in detail via single-axon reconstructions, which suggested that the terminal portions were confined to the ganglionic layer of the dorsal corpus. No labeled terminals were observed outside the caudal corpus cerebelli. Tracer applications to the dorsal molecular layer resulted in labeled cells not only in the ganglionic layer and the granule cell layer of the dorsal corpus but also in the ganglionic layer of the ventral corpus. The latter finding confirms the presence of intrinsic projections from the ventral region to the dorsal region in the caudal corpus cerebelli. We further revealed that the intrinsic projection neurons are Purkinje cells by immunohistochemistry for zebrin II (aldolase C), which is a marker of Purkinje cells, combined with tracer injections into the dorsal corpus. Unlike injections into the ventral corpus, injections into the dorsal corpus resulted in labeled terminals in extracerebellar structures, such as the nucleus of the medial longitudinal fascicle and reticular formation. The present study suggests that indirect inputs from different telencephalic parts received and processed by distinct regions of caudal corpus cerebelli are sent out of the corpus through the efferent neurons in the dorsal corpus.


2011 ◽  
Vol 100 (3) ◽  
pp. 82a
Author(s):  
Don Patrick Bischop ◽  
Céline Roussel ◽  
Serge Schiffmann ◽  
David Gall

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Antoine M Valera ◽  
Francesca Binda ◽  
Sophie A Pawlowski ◽  
Jean-Luc Dupont ◽  
Jean-François Casella ◽  
...  

Motor coordination is supported by an array of highly organized heterogeneous modules in the cerebellum. How incoming sensorimotor information is channeled and communicated between these anatomical modules is still poorly understood. In this study, we used transgenic mice expressing GFP in specific subsets of Purkinje cells that allowed us to target a given set of cerebellar modules. Combining in vitro recordings and photostimulation, we identified stereotyped patterns of functional synaptic organization between the granule cell layer and its main targets, the Purkinje cells, Golgi cells and molecular layer interneurons. Each type of connection displayed position-specific patterns of granule cell synaptic inputs that do not strictly match with anatomical boundaries but connect distant cortical modules. Although these patterns can be adjusted by activity-dependent processes, they were found to be consistent and predictable between animals. Our results highlight the operational rules underlying communication between modules in the cerebellar cortex.


Development ◽  
2002 ◽  
Vol 129 (9) ◽  
pp. 2223-2232 ◽  
Author(s):  
Joshua B. Rubin ◽  
Yoojin Choi ◽  
Rosalind A. Segal

Sonic hedgehog promotes proliferation of developing cerebellar granule cells. As sonic hedgehog is expressed in the cerebellum throughout life it is not clear why proliferation occurs only in the early postnatal period and only in the external granule cell layer. We asked whether heparan sulfate proteoglycans might regulate sonic hedgehog-induced proliferation and thereby contribute to the specialized proliferative environment of the external granule cell layer. We identified a conserved sequence within sonic hedgehog that is essential for binding to heparan sulfate proteoglycans, but not for binding to the receptor patched. Sonic hedgehog interactions with heparan sulfate proteoglycans promote maximal proliferation of postnatal day 6 granule cells. By contrast, proliferation of less mature granule cells is not affected by sonic hedgehog-proteoglycan interactions. The importance of proteoglycans for proliferation increases during development in parallel with increasing expression of the glycosyltransferase genes, exostosin 1 and exostosin 2. These data suggest that heparan sulfate proteoglycans, synthesized by exostosins, may be critical determinants of granule cell proliferation.


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