@article {1584,
	title = {Extinction recall of fear memories formed before stress is not affected despite higher theta activity in the amygdala.},
	journal = {Elife},
	volume = {7},
	year = {2018},
	month = {2018 08 13},
	abstract = {<p>Stress is known to exert its detrimental effects not only by enhancing fear, but also by impairing its extinction. However, in earlier studies stress exposure preceded both processes. Thus, compared to unstressed animals, stressed animals had to extinguish fear memories that were strengthened by prior exposure to stress. Here, we dissociate the two processes to examine if stress specifically impairs the acquisition and recall of fear extinction. Strikingly, when fear memories were formed before stress exposure, thereby allowing animals to initiate extinction from comparable levels of fear, recall of fear extinction was unaffected. Despite this, we observed a persistent increase in theta activity in the BLA. Theta activity in the mPFC, by contrast, was normal. Stress also disrupted mPFC-BLA theta-frequency synchrony and directional coupling. Thus, in the absence of the fear-enhancing effects of stress, the expression of fear during and after extinction reflects normal regulation of theta activity in the mPFC, not theta hyperactivity in the amygdala.</p>
},
	keywords = {Amygdala, Animals, Extinction, Psychological, Fear, Male, Memory, Mental Recall, Prefrontal Cortex, Rats, Sprague-Dawley, Stress, Physiological, Theta Rhythm},
	issn = {2050-084X},
	doi = {10.7554/eLife.35450},
	author = {Rahman, Mohammed Mostafizur and Shukla, Ashutosh and Chattarji, Sumantra}
}
@article {1590,
	title = {Repeated social stress leads to contrasting patterns of structural plasticity in the amygdala and hippocampus.},
	journal = {Behav Brain Res},
	volume = {347},
	year = {2018},
	month = {2018 07 16},
	pages = {314-324},
	abstract = {<p>Previous studies have demonstrated that repeated immobilization and restraint stress cause contrasting patterns of dendritic reorganization as well as alterations in spine density in amygdalar and hippocampal neurons. Whether social and ethologically relevant stressors can induce similar patterns of morphological plasticity remains largely unexplored. Hence, we assessed the effects of repeated social defeat stress on neuronal morphology in basolateral amygdala (BLA), hippocampal CA1 and infralimbic medial prefrontal cortex (mPFC). Male Wistar rats experienced social defeat stress on 5 consecutive days during confrontation in the resident-intruder paradigm with larger and aggressive Wild-type Groningen rats. This resulted in clear social avoidance behavior one day after the last confrontation. To assess the morphological consequences of repeated social defeat, 2 weeks after the last defeat, animals were sacrificed and brains were stained using a Golgi-Cox procedure. Morphometric analyses revealed that, compared to controls, defeated Wistar rats showed apical dendritic decrease in spine density on CA1 but not BLA. Sholl analysis demonstrated a significant dendritic atrophy of CA1 basal dendrites in defeated animals. In contrast, basal dendrites of BLA pyramidal neurons exhibited enhanced dendritic arborization in defeated animals. Social stress failed to induce lasting structural changes in mPFC neurons. Our findings demonstrate for the first time that social defeat stress elicits divergent patterns of structural plasticity in the hippocampus versus amygdala, similar to what has previously been reported with repeated physical stressors. Therefore, brain region specific variations may be a universal feature of stress-induced plasticity that is shared by both physical and social stressors.</p>
},
	keywords = {Amygdala, Animals, Atrophy, Avoidance Learning, CA1 Region, Hippocampal, Dendritic Spines, Dominance-Subordination, Male, Neuronal Plasticity, Prefrontal Cortex, Pyramidal Cells, Rats, Wistar, Stress, Psychological},
	issn = {1872-7549},
	doi = {10.1016/j.bbr.2018.03.034},
	author = {Patel, D and Anilkumar, S and Chattarji, S and Buwalda, B}
}
