Focused Ultrasound Modulates Dopamine in a Mesolimbic Reward Circuit

Area of Science:

• Neuroscience
• Biomedical Engineering

Background:

• Dopamine is crucial for reward and motivation; its pathway dysfunction is implicated in addiction.
• Low-intensity focused ultrasound (LIFU) affects brain activity, but its impact on dopamine neurotransmission remains unclear.

Purpose of the Study:

• To investigate the effects of varying LIFU intensities on dopamine release in the mesolimbic pathway.
• To determine if LIFU can selectively modulate dopamine levels in specific brain regions.

Main Methods:

• Applied 2-minute LIFU at 6.5, 13, and 26 W/cm² to the prelimbic cortex (PLC) in rodents.
• Measured dopamine release in the nucleus accumbens (NAc) core using fast-scan cyclic voltammetry.
• Utilized anatomical controls and histological analysis to confirm specificity and safety.

Main Results:

• LIFU at 13 W/cm² significantly reduced NAc core dopamine release by ~50% for up to 2 hours.
• Higher (26 W/cm²) and lower (6.5 W/cm²) intensities showed less or no dopamine inhibition, respectively.
• LIFU effects were specific to the NAc core, with no changes in caudate or NAc shell dopamine, and no observed cell damage or thermal effects.

Conclusions:

• Moderate-intensity LIFU offers a noninvasive method for targeted modulation of mesolimbic dopamine circuits.
• This technique holds promise for future therapeutic strategies for addiction and other psychiatric disorders affecting dopamine pathways.