Beta-adrenergic receptors ([beta]-ARs) prime hippocampal synapses to stabilize long-term potentiation (LTP). This "metaplasticity" can persist for 1-2 h after pharmacologic activation of [beta]-ARs. It requires activation of PKA (cAMP-dependent protein kinase) during [beta]-AR priming. A-kinase anchoring proteins (AKAPs) tether PKA to…

Netrin-1 was initially characterized as an axon guidance molecule that is essential for normal embryonic neural development; however, many types of neurons continue to express netrin-1 in the postnatal and adult mammalian brain. Netrin-1 and the netrin receptor DCC are both enriched at synapses. In the adult hippocampus, activity-dependent…

Conditioned fear memories that are context-specific shortly after conditioning generalize over time. We exposed rats to a context reminder 30 d after conditioning, which served to reinstate context-specificity, and investigated how this reminder alters retrieval-induced activity in the hippocampus and anterior cingulate cortex (aCC) relative to a…

A learning experience may lead to changes in behavior during the experience, and also to memory expressed at a later time. Are signals causing changes in behavior during the learning experience related to the formation and expression of memory? We examined this question, using learning that food is inedible in "Aplysia." Treatment of an…

Anxiety disorders emerge early, and girls are significantly more likely to develop anxiety compared to boys. However, sex differences in fear during development are poorly understood. Therefore, we investigated juvenile male and female rats in the relapse behaviors following extinction of conditioned fear. In all experiments, 18-d-old rats first…

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…

Safety signals provide "relief" through predicting the absence of an aversive event. At issue is whether these signals also act as instrumental reinforcers. Four experiments were conducted using a free-operant lever-press avoidance paradigm in which each press avoided shock and was followed by the presentation of a 5-sec auditory safety…

To this day, it remains unresolved whether experimental amnesia reflects failed memory storage or the inability to retrieve otherwise intact memory. Methodological as well as conceptual reasons prevented deciding between these two alternatives: The absence of recovery from amnesia is typically taken as supporting storage impairment…

The activation of cAMP-responsive element-binding protein (CREB)-dependent gene expression is thought to be critical for the formation of different types of long-term memory. To explore the consequences of chronic enhancement of CREB function on spatial memory in mammals, we examined spatial navigation in bitransgenic mice that express in a…

Recent evidence suggests that rats require an intact hippocampus in order to recognize familiar objects when they encounter them again in a different context. The two experiments reported here further examined how changes in context affect rats' performance on the novel-object preference (NOP) test of object-recognition memory, and how those…

Hippocampal long-term potentiation (LTP) can be dissociated in early-LTP lasting 4-5 h and late-LTP with a duration of more than 8 h, the latter of which requires protein synthesis and heterosynaptic activity during its induction. Previous studies in vivo have shown that early-LTP in the dentate gyrus can protein synthesis-dependently be…