Deep brain stimulation affects conditioned and unconditioned anxiety in different brain areas

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Psychiatry

Background:

• Deep brain stimulation (DBS) of the nucleus accumbens (NAc) is used for refractory obsessive-compulsive disorder (OCD).
• Rapid anxiety symptom reduction is observed clinically after DBS, but the specific brain targets responsible remain unclear.
• Understanding differential effects on innate versus learned anxiety is crucial for optimizing DBS therapy.

Purpose of the Study:

• To investigate the anxiolytic effects of DBS in different brain regions.
• To determine if DBS differentially impacts unconditioned (innate) and conditioned (learned) anxiety.
• To identify the specific brain areas mediating the anxiolytic effects of DBS.

Main Methods:

• Rats received high-frequency DBS in five brain areas: NAc core, NAc shell, bed nucleus of the stria terminalis (BNST), internal capsule (IC), and ventral medial caudate nucleus (CAU).
• Unconditioned anxiety was assessed using the elevated plus maze.
• Conditioned anxiety was measured with the Vogel conflict test, and locomotor activity was monitored.

Main Results:

• DBS in the ventral medial caudate nucleus (CAU) reduced both conditioned and unconditioned anxiety.
• DBS of the internal capsule (IC) specifically decreased conditioned anxiety.
• DBS of the NAc or BNST did not significantly affect anxiety levels, though NAc core stimulation increased locomotor activity and BNST stimulation decreased it.

Conclusions:

• DBS can have differential effects on conditioned and unconditioned anxiety based on the targeted brain region.
• The internal capsule (IC) appears to be a key target for reducing conditioned anxiety.
• These findings suggest that the anxiolytic effects of DBS in OCD patients may be mediated by the IC rather than the NAc.