Phase-locked dual-band vibration bursts strengthen anti-kindling by vibrotactile coordinated reset stimulation in a spiking network model

Parkinsons disease and related movement disorders are accompanied by pathologically synchronized neuronal activity in cortico-basal ganglia circuits. Coordinated reset (CR) stimulation was derived computationally as a means of suppressing such activity at its source, by resetting the phases of the subpopulations of a synchronized network at staggered times. Under spike-timing-dependent plasticity (STDP), the resulting decorrelated firing depresses excitatory coupling and establishes a weakly coupled, desynchronized state that outlasts stimulation, a process termed anti-kindling. Sustained post-stimulation benefit has been demonstrated for electrical CR stimulation in parkinsonian primates and in proof-of-concept patient studies, and vibrotactile CR (vCR) stimulation realizes the same principle non-invasively through bursts of fingertip vibration. The deployed vCR protocol employs a carrier frequency of 250 Hz, which preferentially recruits Pacinian afferents. Because Pacinian receptive fields extend substantially beyond the stimulated digit, inputs originating at adjacent fingertips converge on overlapping regions of the target population, which degrades the spatial separation on which CR depends. Here we examine whether the spectral composition of the individual burst, independent of the stimulation schedule, governs the magnitude of anti-kindling. In a Hodgkin-Huxley network with STDP, driven through a two-channel model of fast-adapting afferents, a dual-band burst superimposing a 30 Hz component on the 250 Hz carrier yielded the lowest post-stimulation coupling among eleven vCR patterns, at one third of the carriers drive power. Recruitment of focal Meissner afferents by the 30 Hz component restricts part of the drive to the stimulated subpopulation, and phase locking of that component to the burst envelope generates post-burst pauses that reset the phase of the stimulated neurons. Spectral composition therefore determines both the spatial selectivity of vCR stimulation and its capacity for phase resetting.

Patki, S. A., SKM, V.

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