Abstract
Local field potentials (LFPs) may afford insight into the mechanisms of action of deep brain stimulation (DBS) and potential feedback signals for adaptive DBS. In Parkinson's disease (PD) DBS of the subthalamic nucleus (STN) suppresses spontaneous activity in the beta band and drives evoked resonant neural activity (ERNA). Here, we investigate how STN LFP activities change over time following the onset and offset of DBS. To this end we recorded LFPs from the STN in 14 PD patients during long (mean: 181.2 s) and short (14.2 s) blocks of continuous stimulation at 130 Hz. LFP activities were evaluated in the temporal and spectral domains. During long stimulation blocks, the frequency and amplitude of the ERNA decreased before reaching a steady state after ~70 s. Maximal ERNA amplitudes diminished over repeated stimulation blocks. Upon DBS cessation, the ERNA was revealed as an under-damped oscillation, and was more marked and lasted longer after short duration stimulation blocks. In contrast, activity in the beta band suppressed within 0.5 s of continuous DBS onset and drifted less over time. Spontaneous activity was also suppressed in the low gamma band, suggesting that the effects of high frequency stimulation on spontaneous oscillations may not be selective for pathological beta activity. High frequency oscillations were present in only six STN recordings before stimulation onset and their frequency was depressed by stimulation. The different dynamics of the ERNA and beta activity with stimulation imply different DBS mechanisms and may impact how these activities may be used in adaptive feedback.
Highlights
Deep brain stimulation (DBS) has proven a successful treatment for advanced Parkinson's Disease (PD) since it was pioneered by Alim-Louis Benabid in 1987 (Lozano et al, 2019; Okun, 2012)
Note that the absence of evoked resonant neural activity (ERNA) in three subthalamic nucleus (STN) is unlikely to be due to a weaker stimulation amplitude
We describe these dynamics in greater detail, demonstrating that steady state frequency and amplitude are reached after a minute or so of stimulation, and show a previously unreported further diminution of maximal ERNA amplitude when long duration blocks of stimulation are repeated
Summary
Deep brain stimulation (DBS) has proven a successful treatment for advanced Parkinson's Disease (PD) since it was pioneered by Alim-Louis Benabid in 1987 (Lozano et al, 2019; Okun, 2012). The mechanisms of action of DBS remain largely unexplained (Muthuraman et al, 2018). This is important as DBS can elicit stimulation-related side effects that include speech impairment, neuropsychiatric symptoms and paradoxical worsening of motor functions (Chen et al, 2006a; Okun, 2012; Parsons et al, 2006). There has been much recent interest in the possibility of controlling DBS using feedback from electrophysiological signals (Bouthour et al, 2019; Little and Brown, 2020; Lozano et al, 2019)
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