Subcallosal cingulate deep brain stimulation evokes two distinct cortical responses via differential white matter...

Area of Science:

• Neuroscience
• Neurosurgery
• Psychiatry

Background:

• Subcallosal cingulate (SCC) deep brain stimulation (DBS) shows promise for treating refractory depression.
• Clinical success in SCC DBS is linked to activating adjacent white matter, generating cortical evoked potentials (EPs).
• The specific white matter pathways responsible for driving these EPs remain unidentified.

Purpose of the Study:

• To investigate which white matter pathways, specifically the forceps minor (FM) or cingulum bundle (CB), are activated by SCC DBS.
• To correlate selective fiber bundle activation with distinct cortical evoked potentials (EPs).

Main Methods:

• Individualized biophysical models were used to target either the FM or CB.
• Unilateral 2 Hz stimulation was applied to seven patients with treatment-resistant depression who responded to SCC DBS.
• 256-sensor scalp electroencephalography recorded cortical evoked potentials (EPs).

Main Results:

• Two distinct EPs were identified: a 120 ms symmetric response and a 60 ms asymmetric response.
• Activation of the forceps minor (FM) correlated with the symmetric EPs.
• Activation of the cingulum bundle (CB) correlated with the asymmetric EPs.

Conclusions:

• These findings support model predictions regarding the predominant activation of FM and CB by clinical SCC DBS.
• This study provides the first direct evidence linking specific cortical evoked potentials to the selective activation of distinct white matter fiber bundles in SCC DBS.
• Understanding these pathway-EP relationships can refine DBS targeting for improved depression treatment outcomes.