Activity-dependent structural plasticity after aversive experiences in amygdala and auditory cortex pyramidal neurons

Area of Science:

• Neuroscience
• Cell Biology
• Learning and Memory

Background:

• The brain's plasticity allows it to change with experience, particularly during learning.
• Dendritic spine remodeling is crucial for memory formation, but its direct link to neuronal activity remains unclear.
• Previous studies on fear conditioning (FC) observed spine changes, but lacked specificity regarding active neurons.

Purpose of the Study:

• To investigate structural plasticity in neurons specifically activated during fear conditioning.
• To differentiate structural changes in active versus inactive neurons within key brain regions.
• To advance methods for linking experience-driven neural activity to physical brain alterations.

Main Methods:

• Utilized Arc-dVenus transgenic mice to identify activity-labeled neurons (Arc+) during FC.
• Applied targeted fluorescent microinjections to Arc+ and neighboring Arc- neurons.
• Analyzed dendritic spine density in the basolateral amygdala (BLA) and auditory association cortex (TeA).

Main Results:

• Neurons active during FC (Arc+) showed reduced thin and mushroom spine densities compared to inactive neurons (Arc-).
• This effect was consistent across both sexes and in both cued and uncued footshock conditions.
• Structural plasticity differences were observed in both the BLA and TeA.

Conclusions:

• Neuronal activity, specifically during fear conditioning, is associated with a reduction in dendritic spine density.
• This finding highlights a direct relationship between experience-induced neural activity and structural modifications.
• The study provides a novel methodological approach to study experience-dependent structural plasticity in the brain.