Novelty detection, a critical computation within the medial temporal lobe (MTL) memory system, necessarily depends on prior experience. The current study used functional magnetic resonance imaging (fMRI) in humans to investigate dynamic changes in MTL activation and functional connectivity as experience with novelty accumulates. fMRI data were…

There are significant sex differences in vulnerability to develop fear-related anxiety disorders. Females exhibit twice the rate of post-traumatic stress disorder (PTSD) as males and sex differences have been observed in fear extinction learning in both humans and rodents, with a failure to inhibit fear emerging as a precipitating factor in the…

Spontaneous recovery in extinction appears to be inversely related to the acquisition-to-extinction interval, but it remains unclear why this is the case. Rat subjects trained with one of three interference paradigms exhibited less spontaneous recovery of the original response after delayed than immediate interference, regardless of whether…

The present study investigates the fear memory resulting from the interaction of a stressful experience and the retrieval of an established fear memory trace. Such a combination enhanced both fear expression and fear retention in adult Wistar rats. Likewise, midazolam intra-basolateral amygdala (BLA) infusion prior to stress attenuated the…

The apolipoprotein E4 ("APOE-[epsilon]4") allele is the strongest genetic risk factor for developing late-onset Alzheimer's disease, and may predispose individuals to Alzheimer's-related cognitive decline by affecting normal brain function early in life. To investigate the impact of human APOE alleles on cognitive performance in mice, we trained…

The perineuronal net (PNN) surrounds neurons in the central nervous system and is thought to regulate developmental plasticity. A few studies have shown an involvement of the PNN in hippocampal plasticity and memory storage in adult animals. In addition to the hippocampus, plasticity in the medial prefrontal cortex (mPFC) has been demonstrated to…

The prefrontal cortex (PFC) plays a critical role in cognitive functions, including working memory, attention regulation, behavioral inhibition, as well as memory storage. The functions of PFC are very sensitive to norepinephrine (NE), and even low levels of endogenously released NE exert a dramatic influence on the functioning of the PFC.…

We investigated whether reexposure to an amnestic agent would reverse amnesia for extinction of learned fear similar to that of a reactivated memory. When cycloheximide (CHX) was administered immediately after a brief cue-induced memory reactivation (15 sec) and an extended extinction session (12 min) rats showed retrograde amnesia for both…

In "Aplysia," repeated trials of aversive stimuli produce long-term sensitization (LTS) of defensive reflexes and suppression of feeding. Whereas the cellular underpinnings of LTS have been characterized, the mechanisms of feeding suppression remained unknown. Here, we report that LTS training induced a long-term decrease in the excitability of…

We investigated the role of cholinergic neurotransmission in olfactory fear learning. Mice receiving pairings of odor and foot shock displayed fear to the trained odor the following day. Pretraining injections of the nicotinic antagonist mecamylamine had no effect on subsequent freezing, while the muscarinic antagonist scopolamine significantly…

The anaphase promoting complex/cyclosome (APC/C) is an E3 ligase regulated by Cdh1. Beyond its role in controlling cell cycle progression, APC/C-Cdh1 has been detected in neurons and plays a role in long-lasting synaptic plasticity and long-term memory. Herein, we further examined the role of Cdh1 in synaptic plasticity and memory by generating…

Storage of information into long-term memory (LTM) usually requires at least two waves of transcription in many species. However, there is no clear evidence of this phenomenon in insects, which are influential models for memory studies. We measured retention in honeybees after injecting a transcription inhibitor at different times before and after…

Considerable evidence has demonstrated that transient receptor potential (TRP) channels play vital roles in sensory neurons, mediating responses to various environmental stimuli. In contrast, relatively little is known about how TRP channels exert their effects in the central nervous system to control complex behaviors. This is also true for the…

In humans recognition memory deficits, a typical feature of diencephalic amnesia, have been tentatively linked to mediodorsal thalamic nucleus (MD) damage. Animal studies have occasionally investigated the role of the MD in single-item recognition, but have not systematically analyzed its involvement in other recognition memory processes. In…

Despite extensive evidence that appetitive memories undergo reconsolidation, two notable failures to observe reconsolidation have been reported: instrumental responding and goal-tracking. However, these studies do not provide conclusive evidence for a lack of memory reconsolidation due to the numerous boundary conditions that dictate whether a…