Kavli Affiliate: Philip Starr
| Authors: James J. Sermon, Maria Olaru, Juan Anso, Simon Little, Rafal Bogacz, Philip A. Starr, Timothy Denison and Benoit Duchet
| Summary:
Background Entrainment of brain oscillations has been hypothesised as a potential mechanism of neuromodulation. While neuromodulation has been shown to be an effective therapy for a variety of pathologies, there is no algorithmic approach to programming neurostimulators for specific neurological disorders. This is due in part to the lack of understanding of the effects of stimulation on neuronal rhythms. Counterintuitively, cortical finely-tuned gamma oscillations around 75Hz have been reported to be entrained at 65Hz during 130Hz deep brain stimulation (DBS) in patients with Parkinson’s disease (PD). Objective/Methods Here, we demonstrate that these observations are consistent with 1:2 entrainment, which is a special case of sub-harmonic entrainment predicted by synchronisation theory. We fit a coupled neuronal population model to selected features characterising a PD patient’s off-stimulation finely-tuned gamma rhythm recorded through electrocorticography. Results Our model predicts the patient-specific regions of entrainment (Arnold tongues) in the stimulation frequency/amplitude space. We show that the resulting patient-specific neural circuit model exhibits 1:2 entrainment when stimulation is provided at 130Hz. Furthermore, we verify keys features of the 1:2 Arnold tongue with follow-up recordings from the same patient, such as the loss of 1:2 entrainment beyond a certain stimulation amplitude. Conclusion Our results reveal that periodic DBS in patients can lead to counter-intuitive patterns of neuronal entrainment across stimulation parameters, and that these responses can be predicted by modelling. Should entrainment prove to be an important mechanism of therapeutic stimulation, our modelling framework may reduce the parameter space that clinicians must consider when programming devices for optimal benefit.