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Do learning and retrieval of a memory activate the same neurons? Does the number of reactivated neurons correlate with memory strength? We developed a transgenic mouse that enables the long-lasting genetic tagging of c-fos-active neurons. We found neurons in the basolateral amygdala that are activated during Pavlovian fear conditioning and are reactivated(More)
In contrast to the well-documented acute effects on behavioural sensitivity, chronic effects that persist for weeks or even months after the cessation of the stressor received relatively little attention. This study aimed at the long-term effects of a severe stressor, i.e. social defeat followed by individual housing. Defeated and subsequently individually(More)
BACKGROUND Episodic memories are encoded within hippocampal and neocortical circuits. Retrieving these memories is assumed to involve reactivation of neural ensembles that were established during learning. Although it has been possible to follow the activity of individual neurons shortly after learning, it has not been possible to examine their activity(More)
A more complete understanding of how fear extinction alters neuronal activity and connectivity within fear circuits may aid in the development of strategies to treat human fear disorders. Using a c-fos-based transgenic mouse, we found that contextual fear extinction silenced basal amygdala (BA) excitatory neurons that had been previously activated during(More)
In the present study, we investigated whether synaptic plasticity changes in the hippocampus of depressive-like socially stressed rats could be reversed by chronic antidepressant treatment. To that end, rats were either defeated and subsequently individually housed or subjected to control treatment followed by social housing. After a period of at least 3(More)
The stabilization of long-term memories requires de novo protein synthesis. How can proteins, synthesized in the soma, act on specific synapses that participate in a given memory? We studied the dynamics of newly synthesized AMPA-type glutamate receptors (AMPARs) induced with learning using transgenic mice expressing the GluR1 subunit fused to green(More)
Small changes in the sensory environment, called prepulses, prior to a startle-eliciting stimulus can either inhibit or facilitate the startle reaction. To investigate this apparent discrepancy, a number of characteristics of the acoustic prepulse were varied and the effects on the startle reaction were studied. The results showed that increasing the(More)
The dopamine and glutamate hypotheses are two pharmacological models for schizophrenia. In the present investigations, the prepulse inhibition paradigm was used to evaluate the role of the nucleus accumbens core region in both models. Prepulse inhibition is known to be decreased in schizophrenics, when compared with control patients, and in rats after(More)
The subcellular localization and translation of messenger RNA (mRNA) supports functional differentiation between cellular compartments. In neuronal dendrites, local translation of mRNA provides a rapid and specific mechanism for synaptic plasticity and memory formation, and might be involved in the pathophysiology of certain brain disorders. Despite the(More)
Small changes in the sensory environment, called prepulses, prior to a startle-eliciting stimulus can inhibit or facilitate the startle reaction. Previous studies reported that at large intervals between prepulse and startle stimulus the prepulse facilitates the startle reaction, possibly by means of an orienting response. This was, however, only observed(More)