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Mohaddeseh Ebrahimi-Ghiri

Mohammad Nasehi, Reyhaneh Soltanpour, Mohaddeseh Ebrahimi-Ghiri, Shahram Zarrabian, Mohammad-Reza Zarrindast
Interference effects of transcranial direct current stimulation over the right frontal cortex and adrenergic system on conditioned fear
اثرات تداخلی تحریک جریان مستقیم فراجمجمه ای کورتکس پیشانی راست و سیستم آدرنرژیک بر روی ترس شرطی شده

Rationale The effects of pharmacological interventions on fear memory have widely been studied, but there are very few studies about the effects of brain electrical stimulation on fear memory function. Objective Therefore, our aim was to determine whether anodal/cathodal transcranial direct current stimulation (tDCS) over the right frontal cortex would modify propranolol-induced contextual and auditory fear memory deficits, before or after training. Methods The adult NMRI male mice were randomly assigned into three groups: the sham group, the anodal tDCS group, and the cathodal tDCS group. Fear memories were evaluated using a classical fear conditioning apparatus. Results While the anodal stimulation did not affect fear retrieval, post-training cat hodal stimulation improved fear memory retrieval. Regardless of when propranolol (0.1 mg/kg) was administered, it impaired fear memory retrieval. However, when anodal stimulation and propranolol were applied prior to the training, contextual fear memory retrieval was increased and auditory fear memory was reversed. An enhanced contextual retrieval was also observed when propranolol was administered prior to the training and stimulation occurred after the training. Only when the stimulation occurred prior to the training and propranolol was administered after the training was there a selective improvement in contextual fear memory retrieval, leaving the auditory fear memory retrieval impaired. Interestingly, cathodal stimulation improved the effects of propranolol on auditory fear memory only when it occurred prior to the training. Conclusion The results highlight possible improving ef- fects for anodal/cathodal tDCS on propranolol-induced deficits on fear memories. The timing of the interven- tions related to the specific phases of memory formation is important in modulat ing fear behaviors.



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