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. 2014 Feb 25;8:55. doi: 10.3389/fncel.2014.00055

Figure 5.

Figure 5

Interaction of the excitatory and inhibitory mechanisms in the glomerulus. The cerebellar glomerulus allows the cross-talk of excitatory mossy fiber-granule cell connections and inhibitory Golgi cell-granule cells contacts. (1) glutamate spillover to Golgi cell pre-synaptic mGluRs determines a decrease in GABA release (Mitchell and Silver, 2000b). (2) GABA spillover activates pre-synaptic GABA-B receptors on mossy fiber terminals, causing a decrease in glutamate release (Mitchell and Silver, 2000a). (3) Various modulators of excitatory transmission affect inhibition through mechanism 1, regulating the amount of glutamate released (Maffei et al., 2003; Sola et al., 2004; Prestori et al., 2013). (4) In the same way, modulators of inhibitory transmission affect glutamate release through mechanism 2 (Rossi et al., 2003; Wall, 2003; Brandalise et al., 2012). (5) Protracted inhibition activates post-synaptic GABA-B receptors and determines a decrease in K inward rectifier current, modulating granule cell excitability and its responsiveness to mossy fiber inputs (Rossi et al., 2006). (6) Modulators of tonic and phasic inhibition contributes in regulating the amount of GABA in the synaptic cleft and spilling over to mossy fiber terminals, acting on excitatory transmission through mechanisms 2 and 5.