Dynamic Oscillations Evoked by Subcallosal Cingulate Deep Brain Stimulation

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.

Network Action of Subcallosal Cingulate White Matter Deep Brain Stimulation

“…[49, 50]. Second, we only measure three minutes after stimulation onset due to limitations in the device storage, and we average through those three minutes, diluting away transient dynamics that we’ve reported elsewhere [14]. This likely ignores rich dynamics inside the measured time window and certainly misses slower effects of DBS, like neurotransmitter depletion and plasticity [51], Relatedly, the bilateral stimulation analysed in this study occurred at the end of unilateral experiments, potentially confounding our results with priming effects if the 1 min washout period between conditions was insufficient.…”

“…Here, we clarify the network-level mechanism and find evidence supportive of blockade of signaling along right cingulum bundle over the initial treatment initiation. More effort is needed to understand the dynamics that SCCwm-DBS evokes across scalp measurements [14] and the link to long-term δ - β changes that track with depression symptom recovery [45]. The support model approach taken here can be extended with neural mass models to more directly link tractography, dynamic responses, and candidate DBS mechanisms for likelihood-based inference of long-term therapeutic mechanism.…”

“…Preliminary evidence of evoked responses specific to precise SCCwm-DBS show promise in verifying structural engagement [12] but electrophysiologic signatures at therapeutic stimulation frequencies associated with antidepressant response are needed. Using multimodal electrophysiology, consisting of both invasive and non-invasive recordings, we can now probe network-level effects specific to SCCwm-DBS directly in patients [13, 14]. Intracranial recordings from bidirectional DBS devices can measure oscillatory changes local to the brain target [15, 16, 17], while dense-array scalp EEG can measure oscillatory changes from a subset of regions remote to the brain target [12].…”

Local field potentials in major depressive and obsessive-compulsive disorder: a frequency-based review

“…Left stimulation induced broadband ipsilateral decrease in theta, alpha, beta, and gamma bands and right stimulation effects were restricted to ipsilateral beta and gamma bands decrease ( 25 ). Low band frequencies, typically between 2 and 20 Hz, were observed in SCC and adjacent targets, evolving with stimulation ( 26 ).…”