Colloquium: Non-invasive steerable, deep electrical brain stimulation and phase-locking to probe and treat aberrant brain activities
11 July 2022
Colloquium by Prof. Dr. Nir Grossman, Department of Brain Sciences, Imperial College London
Abstract: Our brain's cognitive and motoric capability is mediated by the coordinated activities of neural cells organized in functional networks. Aberrant activity in functional neural networks hallmarks numerous brain diseases, disrupting the spatiotemporal coordination critical for cognitive and motoric functionalities and dysregulating cellular homeostatic processes in neurons and glia. We pioneer non-invasive neuromodulatory tools to probe and treat aberrant neural network activities with high spatiotemporal precision and efficiency.
I will first present a strategy for non-invasive steerable deep brain stimulation using temporal interference (TI) of kHz-range electric fields. We first validate the TI stimulation in a rodent model using electrophysiological recording and c-Fos imaging. We demonstrate that TI stimulation could selectively mediate activation in deep neural structures of the mice, i.e., the hippocampus, without the overlying cortical neurons. We then translate the TI brain stimulation strategy to humans. We use electric field modelling and measurements in a human cadaver to verify that the locus of the transcranial TI stimulation can be steerably focused in the human hippocampus with minimal exposure to the overlying cortex. We then use functional magnetic resonance imaging (fMRI) to demonstrate the utility of the TI stimulation by non-invasively modulating hippocampal neural activity underpinning the encoding of episodic memory in a healthy human cohort. Finally, we demonstrate the capacity of TI hippocampal stimulation to improve episodic memory accuracy in a similar healthy human cohort.
I will then present a strategy for phase-lock brain stimulation using endpoint-corrected Hilbert transform (ecHT) that can track the instantaneous phase of neural oscillations in real-time. We validate the phase-lock stimulation in people with essential tremor (ET) syndrome, the most common adult movement disorder. We demonstrate transient suppression of ET via transcranial electrical stimulation of the cerebellum phase-locked to the tremor. We show that the tremor suppression is sustained shortly after the end of the stimulation and can be phenomenologically predicted. Finally, we use feature-based statistical learning and neurophysiological modelling to show that the suppression of ET is mechanistically attributed to a disruption of the temporal coherence of the aberrant oscillations in the olivocerebellar loop.
Grossman, Nir, et al. "Noninvasive deep brain stimulation via temporally interfering electric fields." cell 169.6 (2017): 1029-1041.
Schreglmann, Sebastian R., et al. "Non-invasive suppression of essential tremor via phase-locked disruption of its temporal coherence." Nature communications 12.1 (2021): 1-15."
Date and time: Monday, 11th July 2022, 5pm, Online via Zoom