Abstract
Deep brain stimulation (DBS) of subcallosal cingulate white matter (SCCwm) alleviates symptoms of depression, but its mechanistic effects on brain dynamics remain unclear. In this study we used novel intracranial recordings (LFP) in n = 6 depressed patients stimulated with DBS around the SCCwm target, observing a novel dynamic oscillation (DOs). We confirm that DOs in the LFP are of neural origin and consistently evoked within certain patients. We then characterize the frequency and dynamics of DOs, observing significant variability in DO behavior across patients. Under the hypothesis that LFP-DOs reflect network engagement, we characterize the white matter tracts associated with LFP-DO observations and report a preliminary observation of DO-like activity measured in a single patient's electroencephalography (dEEG). These results support further study of DOs as an objective signal for mechanistic study and connectomics guided DBS.
Highlights
Deep brain stimulation (DBS) of subcallosal cingulate white matter (SCCwm) has long term, sustained antidepressant effect in patients with treatment resistant depression (TRD) (Holtzheimer et al, 2012; Riva-Posse et al, 2018; Crowell et al, 2019)
We present a serendipitous observation of dynamic oscillations evoked by DBS initiation in particular anatomical structures that exhibit strong frequency components changing over the course of minutes
dynamic oscillations (DOs) were observed in four of six patients under bilateral DBS using the PC+STM (Figures 3A,B), though significant variability in the dynamics were evident across all six patients (Figure 5)
Summary
Deep brain stimulation (DBS) of subcallosal cingulate white matter (SCCwm) has long term, sustained antidepressant effect in patients with treatment resistant depression (TRD) (Holtzheimer et al, 2012; Riva-Posse et al, 2018; Crowell et al, 2019). Short-term randomized control trials (RCTs) studying DBS of the broad SCC region have far been equivocal (Holtzheimer et al, 2017), one contributing factor may be inconsistent stimulation of widespread networks traversed by SCCwm (Riva-Posse et al, 2018; Howell et al, 2019; Tsolaki et al, 2021). Objective measurements of network effects evoked by DBS in the SCC are needed to resolve the apparent contradiction in demonstrated efficacy and test tractography-based hypotheses of therapy (Choi et al, 2015; Waters et al, 2018). Studies identifying oscillations evolving over time (Schiff et al, 2000; Wiest et al, 2020) suggest higher-order characterizations are needed to accurately characterize brain network responses to DBS.
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