Dual Engram Architecture within a Single Striatal Cell Type Distinctly Controls Alcohol Relapse and Extinction

Area of Science:

• Neuroscience
• Addiction Research
• Memory

Background:

• Relapse is a significant challenge in addiction treatment, often linked to persistent drug-associated memories.
• Behavioral therapies like extinction training aim to reduce relapse by forming competing memories, but their neural basis is unclear.

Purpose of the Study:

• To investigate the neural mechanisms underlying opposing memory formation and storage in addiction and extinction.
• To identify specific neuronal ensembles and synaptic changes involved in relapse and extinction behaviors.

Main Methods:

• Utilized engram-tagging tools in mice to identify and manipulate neuronal ensembles.
• Investigated the role of direct-pathway medium spiny neurons (dMSNs) in the striatum.
• Examined synaptic plasticity in corticostriatal pathways.

Main Results:

• Identified two distinct dMSN ensembles within the striatal matrix and striosome compartments encoding opposing alcohol-related memories.
• Demonstrated that matrix-enriched dMSNs promote relapse, while striosome-enriched dMSNs suppress it.
• Found that persistent synaptic strengthening in corticostriatal synapses underlies relapse-promoting memories, and mimicking this plasticity triggers relapse.

Conclusions:

• Uncovered a dual-engram architecture within dMSNs governing addiction relapse and extinction.
• Provided a mechanistic framework for how competing memories regulate drug-seeking behavior.
• Highlighted potential therapeutic targets for modulating relapse through distinct neuronal ensembles and synaptic mechanisms.