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…

[alpha]CaMKII[superscript T286A] mutant mice lack long-term potentiation (LTP) in the hippocampal CA1 region and are impaired in spatial learning. In situ hybridization confirms that the mutant mice show the same developmental expression of [alpha]CaMKII as their wild-type littermates. A simple hypothesis would suggest that if LTP is a substrate…

In three experiments using the barpress conditioned suppression task with albino rats, we studied the renewal (relapse) of conditioned fear in an ABA fear-renewal paradigm. We found that explicitly unpaired (EU) deliveries of conditioned stimuli (CSs) and unconditioned stimuli (USs) in Context B thwarted fear renewal in Context A. Evidence…

Exposure to an enriched environment (EE) has been shown to induce cortical plasticity. Considerable amount of research is focused on the effects of EE in the hippocampus; however, effects of EE on other brain regions and the mechanisms involved are not well known. To investigate this, we induced cortical plasticity by placing mice in an EE for one…

To obtain evidence linking long-term potentiation (LTP) and memory, we examined whether LTP induction modifies functional relationship among neurons in the rat hippocampus. In contrast to neurons in low-frequency stimulated or AP5-treated slices, LTP induction altered "functional connectivity," as defined by the degree of synchronous firing, among…

The neural pathways that convey conditioned stimulus (CS) information to the cerebellum during eyeblink conditioning have not been fully delineated. It is well established that pontine mossy fiber inputs to the cerebellum convey CS-related stimulation for different sensory modalities (e.g., auditory, visual, tactile). Less is known about the…

Conditional directives are used by speakers to instruct hearers which actions are to be taken should certain events occur. The authors demonstrate that conditional directives are distinct from indicative conditionals in which speakers predict what is likely to be observed should certain events occur. The 1st set of experiments shows that goal…

Olfactory discrimination (OD) learning consists of two phases: an initial N-methyl-d-aspartate (NMDA) receptor--sensitive rule-learning phase, followed by an NMDA receptor (NMDAR)--insensitive pair-learning phase. The rule-learning phase is accompanied by changes in the composition and function of NMDARs at synapses in the piriform cortex,…

The Barnes maze is a spatial memory task that requires subjects to learn the position of a hole that can be used to escape the brightly lit, open surface of the maze. Two experiments assessed the relative importance of spatial (extra-maze) versus proximal visible cues in solving the maze. In Experiment 1, four groups of mice were trained either…

Deletions, translocations, or point mutations in the CREB-binding protein (CBP) gene have been associated with Rubinstein-Taybi Syndrome; a human developmental disorder characterized by retarded growth and reduced mental function. To examine the role of CBP in memory, transgenic mice were generated in which the CaMKII[alpha] promoter drives…

The effects of stress (restraint plus tail shock) on hippocampus-dependent trace eyeblink conditioning and hippocampal excitability were examined in C57BL/6 male mice. The results indicate that the stressor significantly increased the concentration of circulating corticosterone, the amount and rate of learning relative to nonstressed conditioned…

Investigates memory storage and molecular nature of associative-memory formation by analyzing Pavlovian conditioning in marine snails and rabbits. Presented is the design of a computer-based memory system (neural networks) using the rules acquired in the investigation. Reports that the artificial network recognized patterns well. (YP)

Learning strategy preferences depend upon circulating estrogen levels, with enhanced hippocampus-sensitive place learning coinciding with elevated estrogen levels. The effects of estrogen on strategy may be mediated by fluctuations in GABAergic function, given that inhibitory tone in the hippocampus is low when estrogen is high. We investigated…

A rapidly learned odor discrimination task based on spontaneous foraging behavior of the rat was used to evaluate the role of N-methyl-D-aspartate (NMDA) receptors (NMDARs) in ongoing memory consolidation. Rats were trained in a single session to discriminate among three odors, one of which was associated with palatable food reward. Previous…

Extinction of conditioned fear in animals is the explicit model of behavior therapy for human anxiety disorders, including panic disorder, obsessive-compulsive disorder, and post-traumatic stress disorder. Based on previous data indicating that fear extinction in rats is blocked by quinpirole, an agonist of dopamine D2 receptors, we hypothesized…