Increased level of kynurenic acid is thought to contribute to the development of cognitive deficits in schizophrenia through an α7nAChR-mediated mechanism in the prefrontal cortex (PFC). Yet, it remains unclear to what extent disruption of PFC α7nAChR signaling impacts afferent transmission and its modulation of behavior. Here we found that PFC infusion of methyllycaconitine (MLA, α7nAChR antagonist) shifts ventral hippocampal-induced local field potential (LFP) suppression to LFP facilitation, an effect only observed in adult male rats. Hippocampal stimulation can also elicit a GluN2B-mediated LFP potentiation (when PFC GABAAR is blocked) that is insensitive to MLA. Conversely, PFC infusion of MLA diminished the gain of amygdalar transmission, which is already enabled by postnatal day 30. Behaviorally, the impact of prefrontal MLA on trace fear-conditioning and extinction was also age-related. While freezing behavior during conditioning was reduced by MLA only in adults, it elicited opposite effects in ad...