Understanding the neural code of stress to control anhedonia

Area of Science:

• Neuroscience
• Behavioral Science
• Molecular Psychiatry

Background:

• Anhedonia, a key symptom of major depressive disorder, involves reduced motivation for rewards.
• The precise neural mechanisms underlying anhedonia and its behavioral consequences are not fully understood.
• Individual differences in responses to stress, such as resilience versus susceptibility, offer a model to study anhedonia's neural basis.

Purpose of the Study:

• To investigate the neural code associated with anhedonia and stress resilience.
• To identify neural signatures of susceptibility and resilience in the basolateral amygdala (BLA) and ventral CA1 (vCA1) following social stress.
• To explore the causal role of vCA1-BLA pathways in anhedonic behavior and neural dynamics.

Main Methods:

• High-density electrophysiology was used to record neural activity in the BLA and vCA1 of mice exposed to social stress.
• Neural activity patterns were analyzed during reward-seeking tasks and during rest.
• Optogenetic manipulation of vCA1 inputs to the BLA was performed in susceptible mice.

Main Results:

• Resilient mice showed robust reward-choice discrimination in BLA activity, while susceptible mice displayed rumination-like neural signatures.
• Manipulation of vCA1-BLA pathways in susceptible mice normalized neural dynamics, enhanced resilience-associated activity, and reversed anhedonia.
• Spontaneous BLA activity in susceptible mice revealed more distinct population states, allowing for decoding of stress history and group identity.

Conclusions:

• Population-level neural dynamics in the BLA differentiate between stress-resilient and stress-susceptible individuals.
• Dysfunctional vCA1-BLA circuit activity contributes to anhedonia.
• Targeting vCA1-BLA pathways represents a potential strategy for enhancing resilience and treating anhedonia in major depressive disorder.