The ability to generate memories that persist throughout a lifetime (that is, memory persistence) emerges in early development across species. Although it has been shown that persistent fear memories emerge between late infancy and adolescence in mice, it is unclear exactly when this transition takes place, and whether two major fear conditioning…

Reconsolidation is a time-limited process under which reactivated memory content can be modified. Works focused on studying reconsolidation mainly restrict intervention to the moments immediately after reactivation and to recently acquired memories. However, the brain areas activated during memory retrieval depend on when it was acquired, and it…

Rodents require a minimal time period to explore a context prior to footshock to display plateau-level context fear at test. To investigate whether this rapid fear plateau reflects complete memory formation within that short time-frame, we used the immediate-early gene product Arc as an indicator of hippocampal context memory formation-related…

"Fos" induction during learning labels neuronal ensembles in the hippocampus that encode a specific physical environment, revealing a memory trace. In the cortex and other regions, the extent to which "Fos" induction during learning reveals specific sensory representations is unknown. Here we generate high-quality brain-wide…

The factors influencing resiliency to the development of post-traumatic stress disorder (PTSD) remain to be elucidated. Clinical studies associate PTSD with polymorphisms of the FK506 binding protein 5 (FKBP5). However, it is unclear whether changes in FKBP5 expression alone could produce resiliency or susceptibility to PTSD-like symptoms. In this…

The absence of a2* nicotinic acetylcholine receptors (nAChRs) in oriens lacunosum moleculare (OLM) GABAergic interneurons ablate the facilitation of nicotine-induced hippocampal CA1 long-term potentiation and impair memory. The current study delineated whether genetic mutations of a2* nAChRs ("Chrna2"[superscript L9'S/L9'S] and…

Retrieval of fear memories can be state-dependent, meaning that they are best retrieved if the brain states at encoding and retrieval are similar. Such states can be induced by activating extrasynaptic ?-aminobutyric acid type A receptors (GABAAR) with the broad a-subunit activator gaboxadol. However, the circuit mechanisms and specific subunits…

Emotional states influence how stimuli are interpreted. High anxiety states in humans lead to more negative, threatening interpretations of novel information, typically accompanied by activation of the amygdala. We developed a handling protocol that induces long-lasting high and low anxiety-like states in rats to explore the role of state anxiety…

Amygdala lesions impair, but do not prevent, acquisition of cerebellum-dependent eyeblink conditioning suggesting that the amygdala modulates cerebellar learning. Two-factor theories of eyeblink conditioning posit that a fast-developing memory within the amygdala facilitates slower-developing memory within the cerebellum. The current study tested…

NMDA receptors (NMDARs) are considered critical for the consolidation of extinction but recent work challenges this assumption. Namely, NMDARs are not required for extinction retention in infant rats as well as when extinction training occurs for a second time (i.e., reextinction) in adult rats. In this study, a possible third instance of…

We examined the neural substrates of fear memory formation and maintenance when repeated recall was used to prevent forgetting in young animals. In contrast to adult rats, juveniles failed to show contextual fear responses at 4 d post-fear conditioning. Reconsolidation sessions 3 and 6 d after conditioning restored contextual fear responses in…

The present study investigated how oxytocin (OT) signaling in the central (CeA) and basolateral (BLA) amygdala affects acquisition, expression, and extinction of context-conditioned fear (freezing) in rats. In the first set of experiments, acquisition of fear to a shocked context was impaired by a preconditioning infusion of synthetic OT into the…

Generalization of fear can involve abnormal responding to cues that signal safety and is common in people diagnosed with post-traumatic stress disorder. Differential auditory fear conditioning can be used as a tool to measure changes in fear discrimination and generalization. Most prior work in this area has focused on elevated amygdala activity…

Surviving threats in the environment requires brain circuits for detecting (or anticipating) danger and for coordinating appropriate defensive responses (e.g., increased cardiac output, stress hormone release, and freezing behavior). The bed nucleus of the stria terminalis (BNST) is a critical interface between the "affective…

The neuronal systems that promote protective defensive behaviours have been studied extensively using Pavlovian conditioning. In this paradigm, an initially neutral-conditioned stimulus is paired with an aversive unconditioned stimulus leading the subjects to display behavioural signs of fear. Decades of research into the neural bases of this…