Brain circuit remembers stresses to help shape reactions to them
Researchers at the Icahn School of Medicine at Mount Sinai have identified a previously overlooked brain circuit that helps explain how prior adversity can make the brain more reactive to future stress.
Researchers at the Icahn School of Medicine have discovered a previously unknown brain circuit that explains how prior stress can make individuals more reactive to future stress. Published in Nature, the study used mice to identify the anterior hypothalamic nucleus (AHN), a small brain structure previously thought to regulate basic bodily functions and defensive behaviors.
By using unbiased brain-scanning techniques, the researchers found that the AHN tracked the intensity of stress and became more sensitive in mice with a history of prior stress. Activating or silencing the AHN altered the strength of the animals' defensive responses to later threats. Specifically, increasing AHN activity amplified defensive responses, while decreasing its activity reduced them.
When the pathway connecting the amygdala to the AHN was silenced, prior stress no longer amplified the animals' responses to subsequent threats. This suggests that the AHN plays a crucial role in regulating the intensity of stress responses based on past experiences. While the study focused on mice, the researchers believe that understanding this circuit could lead to new treatments for stress-related disorders such as PTSD in humans.
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