Imaging versus electrographic connectivity in human mood-related fronto-temporal networks

Area of Science:

• Neuroscience
• Neurosurgery
• Psychiatry

Background:

• The effectiveness of psychiatric deep brain stimulation (DBS) is linked to its connectivity with mood-relevant fronto-temporal networks.
• Diffusion-weighted tractography is the standard method for evaluating this connectivity.

Purpose of the Study:

• To investigate the predictive power of intracranial electrophysiology recordings for circuit-wide neuromodulation effects.
• To test the hypothesis that tractography-predicted structural connectivity aligns with stimulation-induced electrophysiological responses.

Main Methods:

• Evoked potentials were recorded using stereo-electroencephalography (sEEG) during single-pulse stimulation of subcallosal cingulate (SCC) and ventral capsule/ventral striatum (VCVS) DBS targets in two patients.
• Patient-specific diffusion-weighted tractography was used to predict structural connectivity between DBS leads and sEEG contacts.
• Electrophysiological responses were compared with tractography-predicted connectivity.

Main Results:

• Strong convergence between evoked potentials and tractography was observed in orbitofrontal, ventromedial prefrontal, and lateral prefrontal cortices for both SCC and VCVS stimulation.
• Discrepancies were noted in the anterior cingulate cortex (ACC), where tractography predicted connectivity for SCC stimulation but no evoked potentials were detected.
• Conversely, tractography predicted no connectivity from VCVS targets to the ACC, yet VCVS stimulation elicited robust evoked potentials.

Conclusions:

• While diffusion-weighted tractography and electrophysiology show significant convergence, differences highlight tractography's limitations in predicting electrophysiological connectivity for SCC and VCVS targets within the mood network.
• This multimodal approach offers valuable insights for surgical targeting and enhances understanding of neuromodulation's network-wide impact.