Oxytocin (OT) is exclusively expressed in hypothalamic neurons, which extensively project their axons to a wide range of forebrain and hindbrain regions. Taking in consideration enormous variety of behavioral effects of OT, executed by only 8000 neurons (rat), it was tempting to speculate about existence of distinct functional modules within the central OT system, controlling distinct (at least extreme) behaviors. To probe this possibility we developed and applied new genetic technique named”virus-mediated genetic activity-induced tagging” (vGAIT), which is based on transcriptional activity of immediate early gene c-fos. The use of vGAIT inbehaving animals allows to genetically tag OT neurons, which were active upon a certain behavior, such as fear. Therefore, employing the paradigm of contextual fear conditioning, we observed an expression of vGAIT-mediated channel rhodopsin 2 (ChR2) in ~ 15% of OT neurons, which were historically activated by associative fear learning. More importantly, we can demonstrate ‘mimicry’ by eliciting an unfreezing behavior response upon activating OT-fibers expressing ChR2 in the central amygdala, which originate from a small fraction of experience-activated OT neurons. Furthermore, the strength and duration of the effect were comparable with blue-light inducedmobility observed in animals with expression of ChR2 in all OT neurons. In conclusion, we have identified a minimal OT neuronal assembly, which is sufficient to illicit a behavior response by an artificial stimulation of experience activated tagged neurons. The universality of this assembly for other types of fear (i.e. social or innate fears) as well as deciphering OT modules for the distinct form of behaviors, such as empathic and pro-social behaviors, remain further investigations.