One experiment with rats explored whether an extinction-cue prevents the recovery of extinguished lever-pressing responses. Initially, rats were trained to perform one instrumental response (R1) for food in Context A, and a different instrumental response (R2) in Context B. Then, responses were extinguished each in the alternate context (R1 in…

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…

It is known from studies outside the brain that upon binding to its receptor, angiotensin-(1-7) elicits the release of prostanoids and nitric oxide (NO). Cyclooxygenase (COX) is a key enzyme that converts arachidonic acid to prostaglandins. Since there are no data available so far on the role of COX-2 in the amygdala, in a first step we…

Previous reports have shown that overexpression of the growth- and plasticity-associated protein GAP-43 improves memory. However, the relation between the levels of this protein to memory enhancement remains unknown. Here, we studied this issue in transgenic mice (G-Phos) overexpressing native, chick GAP-43. These G-Phos mice could be divided at…

Stimulation paradigms that induce perforant path long-term potentiation (LTP) initiate phosphorylation of ERK1/2 and induce expression of a variety of immediate early genes (IEGs). These events are thought to be critical components of the mechanism for establishing the changes in synaptic efficacy that endure for hours or longer. Here we show that…

The research reported here was directed at evaluating whether or not the effectiveness of a Pavlovian unconditioned stimulus (US) in promoting associative learning is reduced if the US is shortly preceded by another occurrence of the same US. (Author)

Several experiments tested the occurrence of the "Kamin effect", i.e., the deficit in performance of an incompletely learned avoidance task, in terms of discrimination (choice) behavior by rats. (Editor/RK)

Repeated, isolated presentations of a stimulus typically reduce the subsequent ability of that cue to become an effective conditioned stimulus. This phenomenon is known as the latent inhibition effect. Four experiments investigate this effect. (Editor/RK)

Grant and Roberts found that houselight presented throughout the delay period on a delayed matching-to-sample task caused pigeons to demonstrate a much lower level of accuracy than was found when the delay was spent in darkness. A series of experiments was carried out to examine possible mechanisms responsible for this light-induced retroactive…

Investigates the nature of the rhythmic process mediating multiple retention deficits in rats, i.e., whether it was induced by a training procedure or based on a pre-existing physiological rhythm. Also concerns the mechanism of the rhythm's effect on retention performance, whether it affects performance factors per se or the retrieval of prior…

This research used tasks analogous to Delayed Matching-to-Sample tasks to study pigeons' Short Term Memory for responses and reinforcers, as well as for more conventional stimuli. The broad question is whether stimulus, response, and reinforcer memories are all influenced in the same way by the same independent variables. (Author/RK)

Extinction of classically conditioned fear, like its acquisition, is active learning, but little is known about its molecular mechanisms. We recently reported that temporal massing of conditional stimulus (CS) presentations improves extinction memory acquisition, and suggested that temporal spacing was less effective because individual CS…