Optimal number of stimulation contacts for coordinated reset neuromodulation

Abstract

In this computational study we investigate coordinated reset (CR) neuromodulation designed for an effective control of synchronization by multi-site stimulation of neuronal target populations. This method was suggested to effectively counteract pathological neuronal synchrony characteristic for several neurological disorders. We study how many stimulation sites are required for optimal CR-induced desynchronization. We found that a moderate increase of the number of stimulation sites may significantly prolong the post-stimulation desynchronized transient after the stimulation is completely switched off. This can, in turn, reduce the amount of the administered stimulation current for the intermittent ON–OFF CR stimulation protocol, where time intervals with stimulation ON are recurrently followed by time intervals with stimulation OFF. In addition, we found that the optimal number of stimulation sites essentially depends on how strongly the administered current decays within the neuronal tissue with increasing distance from the stimulation site. In particular, for a broad spatial stimulation profile, i.e., for a weak spatial decay rate of the stimulation current, CR stimulation can optimally be delivered via a small number of stimulation sites. Our findings may contribute to an optimization of therapeutic applications of CR neuromodulation.

The Influence of the Region of Interest Width on Two‐Dimensional Speckle Tracking–Based Measurements of Strain and Strain Rate

“…This is a reason why the effect of ROI width is stronger on global SC than on global SL. 29 It is known from literature that SC has a broader spread of normal values 8 and a lower reproducibility 30,31 than SL. It seems likely that the higher sensitivity on ROI width described in this study is a factor contributing to these characteristics.…”

“…This length is ROI width dependent in curved ROIs (curvature dependency). 28,29 For example, when the ROI is made wider, the center line of the ROI is shifted outwards. In a curved ROI its length will increase.…”

“…As a result, the measurement will be lower, meaning less negative (global strain = (minimal center line length À maximal center line length)/maximal center line length 9 100). 19,29 Furthermore, the change of the center line length is higher in a circularshaped ROI (SAX) than in a U-shaped ROI (4CH). This is a reason why the effect of ROI width is stronger on global SC than on global SL.…”

“…As the ROI width set by the software is generated in proportion to the ROI radius it is not recommended for general adoption. 29 Criteria for the definition of ROI width are given in the user manual: the ROI should not extend beyond the epicardial border and pericardium should not be included into the ROI. 19 This means that the ROI would have to be adapted to the thinnest myocardial segment and that part of myocardium would be excluded from analysis.…”

Neuronal Synchronization Can Control the Energy Efficiency of Inter-Spike Interval Coding

“…We found that the average mutual information per unit cost is maximized at a relatively small synchronization level (~30%, Figure 7C) and drops quickly as synchronization level increases. Moreover, this finding may aid in the calibration of the desynchronizing stimulation technique, used in deep brain stimulation for the treatment of the abovementioned diseases [93]. Specifically, it may guide the therapists to perform the desynchronization stimulation such that, instead of shifting the activity of underlying network to a relatively asynchronous state (anti-kindling process) [91,93], push it to a mode with a relatively small synchronization level so that the network's energy efficient state can be provoked.…”