DAngeloE+5-2013

Notes about [DAngeloE+5-2013] 1.

1

Egidio D’Angelo, Sergio Solinas, Jonathan Mapelli, Daniela Gandolfi, Lisa Mapelli, and Francesca Prestori. The cerebellar Golgi cell and spatiotemporal organization of granular layer activity. Frontiers in Neural Circuits, 2013. URL: http://journal.frontiersin.org/article/10.3389/fncir.2013.00093/abstract, doi:10.3389/fncir.2013.00093, Notes: DAngeloE+5-2013.html (this file).

This paper has data about of grannule cells and Golgi cells in rat cerebellum. p. 9:

Quantitative Golgi Cell Connection Scheme

On the basis of current knowledge it is possible to generate a quantitative connection scheme for the Golgi cell, which is unique both for its high level of precision and for the quantity of available experimental data. Using morphological measurements, it can be calculated that the rat cerebellar granular layer has a cell density of 4 × 10^6/mm^3 for granule cells and 9300/mm^3 for Golgi cells, with a Golgi cell : granule cell ratio of 1:430 (Korbo et al., 1993). Moreover, the density of the glomeruli is 3 × 10^5/mm^3, and each glomerulus is composed of one mossy fiber terminal, about 53 dendrites from separate granule cells (Jakaband Hamori, 1988), and one or more dendrites from Golgi cells. Network connections can be reconstructed by applying simple rules, most of which can be directly extracted from original works on cerebellar architecture (e.g., see Eccles et al., 1967).

Granule cell connection rules are quite simple and can be summarized as follows: granule cell dendrites cannot reach glomeruli located more than 40 μm away (meanden dritic length : 13.6 μm) and a single granule cell cannot send more than one dendrite into the same glomerulus. Conversely, Golgi cell connection rules are more complex. It can be assumed that only one Golgi cell axon enters a glomerulus, forming inhibitory synapses on all the afferent granule cell dendrites, and that a Golgi cell axon entering a glomerulus cannot access the neighboring glomeruli if they share granule cells with the first one. This should prevent a granule cell from being inhibited twice by the same Golgi cell (see above and Solinas et al., 2010). Each Golgi cell can inhibit as many as 40 different glomeruli and atotal of about 2000 granule cells, accounting for the 1:430 Golgi cell:granule cell ratio and the aforementioned convergence and divergence ratios (see above). Recent calculations seem to indicate a specific organization of excitatory connectivity. Golgi cells were suggested to receive excitatory inputs from about 40 mossy fibers on basal dendrites (Kanichay and Silver, 2008). Moreover, a specific organization is emerging for granule cell inputs through the ascending axons and parallel fibers (Cesana et al., 2010). Golgi cells could receive about 400 connections from the ascending axons of local granule cells on the basal dendrites and another 400 connections through the parallel fibers of local granule cells, which would provide the basis for a powerful feedback circuit. In addition, Golgi cells receive about 1200 parallel fiber contacts on the apical dendrites from transversely organized granular layer fields. It has been calculated that the effectiveness of local granule cells is about 10 times greater than that of an equivalent population located outside the direct afferent field and forming only parallel fiber contacts toward the Golgi cell.