Fear generalization is one of the main symptoms of posttraumatic stress disorder. In rodents, the anterior cingulate cortex (ACC) and the hippocampus (HPC) control the expression of contextual fear memory generalization. Consistently, ACC projections to the ventral HPC contribute to contextual fear generalization. However, the roles of ACC…

Histone acetylation, catalyzed by e, has emerged as a promising therapeutic strategy in Alzheimer's disease (AD). By longitudinally characterizing spatial memory at 3, 6, and 9 mo of age, we show that acute activation and inhibition of the histone acetyltransferase PCAF remediated memory impairments in 3xTG-AD mice in an age-related bidirectional…

Differences in the learning associated transcriptional profiles between mouse strains with distinct learning abilities could provide insight into the molecular basis of learning and memory. The inbred mouse strain DBA/2 shows deficits in hippocampus-dependent memory, yet the transcriptional responses to learning and the underlying mechanisms of…

Plasticity is a neural phenomenon in which experience induces long-lasting changes to neuronal circuits and is at the center of most neurobiological theories of learning and memory. However, too much plasticity is maladaptive and must be balanced with substrate stability. Area CA3 of the hippocampus provides such a balance via hemispheric…

Hippocampal dopamine D1/D5 receptor-dependent destabilization is necessary for object recognition memory (ORM) updating through reconsolidation. Dopamine also regulates hippocampal theta and gamma oscillations, which are involved in novelty and memory processing. We found that, in adult male rats, ORM recall in the presence of a novel object, but…

There are sex differences in anxiety disorders with regard to occurrence and severity of episodes such that females tend to experience more frequent and more severe episodes. Contextual fear learning and generalization are especially relevant to anxiety disorders, which are often defined by expressing fear and/or anxiety in safe contexts. In…

Recent data reveal that the thalamic nucleus reuniens (RE) has a critical role in the extinction of conditioned fear. Muscimol (MUS) infusions into the RE impair within-session extinction of conditioned freezing and result in poor long-term extinction memories in rats. Although this suggests that RE inactivation impairs extinction learning, it is…

Inclusion of male and female subjects in behavioral neuroscience research requires a concerted effort to characterize sex differences in standardized behavioral assays. Sex differences in hippocampus-dependent assays have been widely reported but are still poorly characterized. In the present study, we conducted a parametric analysis of…

The ubiquitin proteasome system (UPS) is a primary mechanism through which proteins are degraded in cells. UPS activity in the dorsal hippocampus (DH) is necessary for multiple types of memory, including object memory, in male rodents. However, sex differences in DH UPS activation after fear conditioning suggest that other forms of learning may…

In hippocampal CA1 neurons of wild-type mice, a short tetanus (15 or 20 pulses at 100 Hz) or a standard tetanus (100 pulses at 100 Hz) to a naive input pathway induces long-term potentiation (LTP) of the responses. Low-frequency stimulation (LFS; 1000 pulses at 1 Hz) 60 min after the standard tetanus reverses LTP (depotentiation [DP]), while LFS…

Neural network dynamics underlying flexible animal behaviors remain elusive. The fruit fly "Drosophila" melanogaster is considered an excellent model in behavioral neuroscience because of its simple neuroanatomical architecture and the availability of various genetic methods. Moreover, "Drosophila" larvae's transparent body…

We observed differences in cognitive functions between middle-aged female and male Wistar rats. Both (like youngsters) discriminated new versus familiar objects, showing similar short- and long-term memory (STM and LTM, respectively). Only females show robust LTM for new location of an object. Both successfully form LTM of inhibitory avoidance,…

Pavlovian fear conditioning is a widely used behavioral paradigm for studying associative learning in rodents. Despite early recognition that subjects may engage in a variety of both conditioned and unconditioned responses, the last several decades have seen the field narrow its focus to measure freezing as the sole indicator of conditioned fear.…

The effect of repetitive training on learned behavior has been an important subject in neuroscience. In instrumental conditioning in mammals, learned action early in training is often goal-driven and controlled by outcome expectancy, but as training progresses, it becomes more habitual and insensitive to outcome devaluation. Similarly, we recently…

Neocortical sleep spindles have been shown to occur more frequently following a memory task, suggesting that a method to increase spindle activity could improve memory processing. Stimulation of the neocortex can elicit a slow oscillation (SO) and a spindle, but the feasibility of this method to boost SO and spindles over time has not been tested.…