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. Author manuscript; available in PMC: 2012 Nov 1.
Published in final edited form as: Neurosci Biobehav Rev. 2011 Jan 14;35(10):2073–2083. doi: 10.1016/j.neubiorev.2010.12.015

Figure 4.

Figure 4

Mechanisms of facilitation and inhibition for FM-FM neurons. A-C. Responses of FM-FM neuron before and during pharmacological blockade of ionotropic glutamate receptors alone (iGluR Block) or in combination with glycine receptor blockade (+Gly Block). iGluR Block eliminates nearly all single tone responses (A,B), but facilitation in response to tone combinations persists (C). Addition of glycine receptor blocker eliminates facilitation (C). Facilitation is independent of glutamatergic inputs to IC neuron. Adapted with permission from Sanchez et al. (2008). D. Proposed origin of FM-FM and other combination-sensitive (CS) responses in IC neurons. Inhibitory interactions originate in nuclei of the lateral lemniscus (NLL) and depend on low-frequency tuned glycinergic inhibition. Inhibitory CS interactions in IC neurons inherit this response property from NLL neurons via glutamatergic synapses. Facilitation in IC neurons depends on low- and high-frequency tuned glycinergic inputs. Used with permission from Peterson et al., (2009); J. Neurophysiol., Am. Physiol. Soc.