Dopamine release and dopamine-related gene expression in the amygdala are modulated by the gastrin-releasing peptide in opposite directions during stress-enhanced fear learning and extinction.

Fear extinction leads to a decrease of originally acquired fear responses after the threat is no longer present. Fear extinction is adaptive and critical for organism's survival, but deficits in extinction may lead to exaggerated fear in animals or post-traumatic stress disorder (PTSD) in humans. Dopamine has recently emerged as essential for fear extinction and PTSD, however the neural circuits serving this dopamine function are only beginning to be investigated, and the dopamine intracellular signaling pathways are unknown.

Abnormal EEG signal energy in the elderly: A wavelet analysis of event-related potentials during a stroop task.

Background: Previous work showed that elderly with excess in theta activity in their resting state electroencephalogram (EEG) are at higher risk of cognitive decline than those with a normal EEG. By using event-related potentials (ERP) during a counting Stroop task, our prior work showed that elderly with theta excess have a large P300 component compared with normal EEG group. This increased activity could be related to a higher EEG signal energy used during this task.

Experience-Regulated Neuronal Signaling in Maternal Behavior.

Maternal behavior is shaped and challenged by the changing developmental needs of offspring and a broad range of environmental factors, with evidence indicating that the maternal brain exhibits a high degree of plasticity. This plasticity is displayed within cellular and molecular systems, including both intra- and intercellular signaling processes as well as transcriptional profiles. This experience-associated plasticity may have significant overlap with the mechanisms controlling memory processes, in particular those that are activity-dependent.

Imbalance in cerebral protein homeostasis: Effects on memory consolidation.

The long-standing hypothesis that memory consolidation is dependent upon de novo protein synthesis is based primarily on the amnestic effects of systemic administration of protein synthesis inhibitors (PSIs). Early experiments on mice showed that PSIs produced interference with memory consolidation that was dependent on the doses of PSIs, on the interval between drug injection and training, and, importantly, on the degree and duration of protein synthesis inhibition in the brain. Surprisingly, there is a conspicuous lack of information regarding the relationship between the duration of protein synthesis inhibition produced by PSIs and memory consolidation in the rat, one of the species most widely used to study memory processes.

Retrieval of Inhibitory Avoidance Memory Induces Differential Transcription of arc in Striatum, Hippocampus, and Amygdala.

Similar to the hippocampus and amygdala, the dorsal striatum is involved in memory retrieval of inhibitory avoidance, a task commonly used to study memory processes. It has been reported that memory retrieval of fear conditioning regulates gene expression of arc and zif268 in the amygdala and the hippocampus, and it is surprising that only limited effort has been made to study the molecular events caused by retrieval in the striatum. To further explore the involvement of immediate early genes in retrieval, we used real-time PCR to analyze arc and zif268 transcription in dorsal striatum, dorsal hippocampus, and amygdala at different time intervals after retrieval of step-through inhibitory avoidance memory.

Two Different Populations within the Healthy Elderly: Lack of Conflict Detection in Those at Risk of Cognitive Decline.

During healthy aging, inhibitory processing is affected at the sensorial, perceptual, and cognitive levels. The assessment of event-related potentials (ERPs) during the Stroop task has been used to study age-related decline in the efficiency of inhibitory processes. Studies using ERPs have found that the P300 amplitude increases and the N500 amplitude is attenuated in healthy elderly adults compared to those in young adults.

Protein synthesis is not required for acquisition, consolidation, and extinction of high foot-shock active avoidance training.

Long-term memory of active avoidance in mice is not disturbed by administration of protein synthesis inhibitors (PSIs) when relatively high levels of training are used, whereas a detrimental effect is produced with lower levels of training. PSIs also disrupt extinction of avoidance behaviors in rodents, but it is not clear whether PSIs also affect this form of learning when the behavior to be extinguished was produced by a high level of training. Experiment 1 demonstrated that rats treated with the PSI cycloheximide (CXM) 30 min before training developed normal acquisition after training with either high or low foot-shock stimulation, but that memory consolidation was hindered only after low foot-shock training.