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The classical fear conditioning is extensively used in preclinical studies as an animal model for post-traumatic stress disorder (PTSD). During the reconsolidation process, when memories are retrieved, the memory becomes susceptible to change and amenable to intervention. Interventions applied during the reconsolidation process triggered by exposure to a conditioned stimulus (CS) primarily lead to a decrease in fear responses triggered only by the exposed CS, without generalizing to other fear-related cues. However, in real-life scenarios, multiple CS's can be linked to fear-inducing events. Therefore, recent studies have focused on the reactivation procedure with an unconditioned stimulus (US), which is believed to result in the reconsolidation of the entire fear memory. Interventions applied during the reconsolidation process that are triggered by US-based retrieval are considered more effective. Grounding on the fear memory studies activated by either CS or US, this review study discussed how acquired fear can be extinguished through behavioral and pharmacological interventions. Additionally, the brain regions involved in fear memory and the impact of gender differences on fear memory were also addressed. The aim of this review was to contribute to the field by exploring more effective treatment approaches for fear disorders. [ABSTRACT FROM AUTHOR]

Newly acquired memory traces have been thought to become stable and resistant to interruption after they are stored in long-term memory. However, according to a recent research drugs such as betaadrenergic receptor antagonists enable memories to be updated and rewritten when administered during consolidation and reconsolidation. Propranolol is a widely used beta-adrenergic receptor antagonist that disrupts the consolidation and reconsolidation processes of memory formation as it inhibits protein synthesis in the central nervous system. This review aims to discuss the memory impairing effect of the systemic and intracerebral administration of propranolol during the consolidation and reconsolidation processes associated with different learning tasks. In doing so, this review will help elucidate the effects of propranolol on different stages of memory formation. Since learning and maladaptive memories underpin some of the most common psychological disorders, such as phobias, post-traumatic stress disorder, addiction, drugseeking behavior, and so on, a thorough understanding of propranolol's memory-impairing effect has significant clinical value and the potential to help people suffering from these disorders. [ABSTRACT FROM AUTHOR]

Objective: The high emetogenicity of chemotherapy results in cancer patients developing anticipatory nausea and vomiting (ANV). ANV is an example of classical conditioning which occurs as a result of associations between contextual cues in the hospital and chemotherapy-induced illness. In this study, we investigated the neural correlates of ANV by assessing c-Fos expression (a putative marker of neuronal activity) after conditioned context aversion (CCA) learning, an animal model of ANV that we have successfully developed. Methods: Twelve-week-old CD1 male mice were divided into two control groups; NaCl-Context B (n=18) and LiCl-Context A (n=18); and one experimental group LiCl-Context B (n=18). During conditioning, animals in the LiCl-Context A group received injections of LiCl in their home cages (Context A). Animals in NaCl-Context B and LiCl-Context B groups received injections of NaCl and LiCl in the conditioning context (Context B), respectively. Six animals of each group were perfused exactly 1 hour after the conditioning for the evaluation of c-Fos expression. CCA memory was tested with the remaining 12 animals in a 15-minute retention trial 72 hours after the conditioning. Amount of water intake was used as an index of aversion. Results: During the retention test, LiCl-Context B group exhibited significantly decreased water consumption compared to the controls (LiCl-Context A and NaCl-Context B), indicative of successful CCA development (p<0.001). c-Fos expression of LiCl-Context B group was significantly higher in the CA1-CA2 (p<0.001) and the dentate gyrus (DG) (p<0.001) subregions of the hippocampus compared to controls. Conclusion: The establishment of an association between a context and illness correlates with specific neuronal c-Fos expression within the CA1-CA2 and DG indicating a role for the hippocampus in the formation of CCA. Future studies should investigate the causal involvement of this brain region in the establishment of CCA. [ABSTRACT FROM AUTHOR]

Objective: Transactive response-DNA binding proteinopathy (TDP-43) has become a hallmark feature in motor neuron diseases. Not only overexpression, but also deletion of the nuclear localization signal (NLS) causes proteinopathic alterations. We employed viral vector mediated gene transfer method for delivery of genes encoding native or mutant TDP-43 to assess motor functions of young adult male and female Sprague-Dawley rats. Methods: Motor neuron specific targeting of AAV9 vectors were achieved by using a cell type specific promoter (UCHL1). While control animals received SF injection (n=10), experimental groups were injected by either native or NLS-deleted viruses (1.77x1012 vg/kg, n=7/each group), on postnatal day 30. Following systemic injection of viruses, motor coordination of animals was evaluated by Rota-rod and modified grip tests for 4 weeks. Then, spatial learning and memory abilities of animals were measured by Morris Water Maze (MWM) test. Results: The number of falls from the rota-rod apparatus was significantly higher in males injected by native TDP-43 than those of controls at 4th week (p<0.05). Grip test scores of females showed no difference between the control and experimental groups. In contrast, scores of the males in the experimental groups were significantly lower (p<0.01) than those of controls. MWM results displayed no significant difference between control and experimental groups in terms of latency to reach the platform and time spent in the target quadrant. Conclusion: Transduction of animals with native or NLS-deleted TDP43 gene sequences results in gender-biased changes in motor functioning and disease onset without cognitive impairments. This relatively low cost, novel model might be helpful in testing therapeutic approaches in motor neuron diseases. [ABSTRACT FROM AUTHOR]