Changes in Appetitive Associative Strength Modulates Nucleus Accumbens, But Not Orbitofrontal Cortex Neuronal...

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Cellular Electrophysiology

Background:

• Learned associations between cues and food rewards drive motivated behaviors.
• Neuronal ensembles are thought to encode these associations.
• Changes in neuronal excitability are implicated in learning, but specific changes in cue-activated ensembles are unclear.

Purpose of the Study:

• To investigate alterations in neuronal excitability within cue-activated ensembles in the orbitofrontal cortex (OFC) and nucleus accumbens (NAc) shell.
• To determine if these excitability changes are dynamic and adapt to associative learning and extinction.

Main Methods:

• Used Fos-GFP mice to identify cue-activated neuronal ensembles in the OFC and NAc shell after appetitive conditioning and extinction.
• Employed whole-cell electrophysiology to measure the intrinsic excitability of GFP+ neurons within these ensembles.

Main Results:

• Sucrose cue exposure activated neuronal ensembles in both the NAc shell and OFC.
• Activated neurons in the NAc shell, but not OFC, showed increased excitability compared to non-activated neurons.
• Following extinction learning, ensemble activation decreased, and altered excitability was no longer observed in either brain area.

Conclusions:

• Learning-induced changes in neuronal ensemble excitability are regulated dynamically and differ across brain regions.
• The nucleus accumbens shell, but not the OFC, exhibits altered neuronal excitability in activated ensembles, which is modulated by associative strength.
• These findings reveal differential regulation and dynamic adaptation of intrinsic excitability in brain areas encoding appetitive memories.