One of the characteristics of depression is a tendency to perceive sensory stimuli and everyday situations in an excessively negative way. But the mechanisms underpinning this "negativity bias," which can fuel the development of depressive symptoms, had previously remained largely unknown. To shed light on the question, scientists from the Institut Pasteur and the CNRS, in collaboration with psychiatrists from Paris Psychiatry and Neurosciences GHU, Inserm and the CEA, decided to explore the amygdala and observe how it functions during depressive episodes. Their findings suggest that a depressive state alters certain specific neural circuits, leading to a reduction in the activity of neurons involved in pleasant perceptions of positive stimuli and an overactivation of those responsible for the perception of negative stimuli. These results, which could pave the way for the development of new drugs for people resistant to conventional therapy, were published in the journal Translational Psychiatry in September 2024.