Of course, these cannot be strictly segregated, and it should be kept in mind that neurons can participate within several networks; Selleck ABT 888 for example, neurons acting with the network underlying social behavior can also contribute to processing within the networks involved in stress and anxiety. Following an early definition proposed by Kupfermann (1979), neuromodulation, unlike

conventional neurotransmission, does not simply excite or inhibit an electrically excitable cell, but is rather involved in altering the effects of other events occurring at the cell. Most reports on the neuromodulatory effects of AVP and OT, however, have up to now only studied effects of external application of these neuropeptides, often resulting in robust changes in spontaneous neuronal activity. However click here such “spontaneous” activity is typically

generated under precise given circumstances in vitro (e.g., changes in external concentrations of Ca2+ or K+) that in vivo may depend on conventional neurotransmission. In strictest sense, these studies can therefore not distinguish between a role of OT and VP as conventional neurotransmitters or as neuromodulators. In this context it is important to keep in mind that neuropeptides typically are thought to be coreleased with other classical neurotransmitters such as glutamate or GABA only at higher frequencies of stimulation (Hökfelt, 1991). Consistently, our findings with the blue light-induced stimulation of endogenous release of oxytocin suggest corelease with glutamate (Knobloch et al., 2012) and a similar scenario may apply for vasopressin. The development of optogenetic methods to specifically stimulate OT and AVP containing projections can here provide a most valuable, and possibly even crucial, tool to dissect the precise neuromodulatory roles of these neuropeptides in situ. AVP and/or OTRs are expressed in different regions of the main and accessory olfactory systems. In the main olfactory epithelium, mRNA for both V1a and V1b receptors has been detected

(Levasseur et al., 2004). Furthermore, in an immortalized cell line displaying the features of immature, migrating olfactory neurons (GN11), activation of OTRs led to the accumulation of inositol phosphates and to the inhibition of an inwardly rectifying potassium currents (Gravati et al., 2010). No studies seem to have addressed a role in the Cell press pheromone-sensitive epithelium of the vomeronasal organ. At the next level, V1a&bRs as well as OTRs are expressed in both the main (MOB) and accessory olfactory bulb (AOB) (Tobin et al., 2010; Vaccari et al., 1998). Although the MOB and AOB receive distinct inputs from, respectively, the olfactory epithelium and vomeronasal organ, their anatomical organizations appear very similar. In both bulbs, mitral cells (MCs) constitute the main relay neurons. Dendrites of mitral cells make excitatory contact with dendrites of local granule cells (GCs) and in return receive inhibitory dendritic inputs from GCs (Figure 3A).