Abstract
Several brain disorders are characterized by abnormally strong neuronal synchrony. Coordinated Reset (CR) stimulation was developed to selectively counteract abnormal neuronal synchrony by desynchronization. For this, phase resetting stimuli are delivered to different subpopulations in a timely coordinated way. In neural networks with spike timing-dependent plasticity CR stimulation may eventually lead to an anti-kindling, i.e., an unlearning of abnormal synaptic connectivity and abnormal synchrony. The spatiotemporal sequence by which all stimulation sites are stimulated exactly once is called the stimulation site sequence, or briefly sequence. So far, in simulations, pre-clinical and clinical applications CR was applied either with fixed sequences or rapidly varying sequences (RVS). In this computational study we show that appropriate repetition of the sequence with occasional random switching to the next sequence may significantly improve the anti-kindling effect of CR. To this end, a sequence is applied many times before randomly switching to the next sequence. This new method is called SVS CR stimulation, i.e., CR with slowly varying sequences. In a neuronal network with strong short-range excitatory and weak long-range inhibitory dynamic couplings SVS CR stimulation turns out to be superior to CR stimulation with fixed sequences or RVS.
Highlights
Strong neuronal synchronization characterizes several brain disorders, e.g., Parkinson’s disease (Lenz et al, 1994; Nini et al, 1995; Hammond et al, 2007), epilepsy (Wong et al, 1986; Schomer and Lopes da Silva, 2010), and tinnitus (Ochi and Eggermont, 1997; Llinas et al, 1999; Weisz et al, 2005; Eggermont and Tass, 2015)
Varying Sequences Boost Coordinated Reset (CR) stimulation Effect To verify whether the SVS CR stimulation is more successful than the rapidly varying sequences (RVS) CR stimulation, the effect of both CR algorithms on the average synaptic weight, Cav, as well as on the synchronization of neuronal activity R has to be investigated
Since we are interested in the long-lasting effects of the CR stimulation period, we will concentrate on the values at the end of the CR-off for the remainder of this work
Summary
Strong neuronal synchronization characterizes several brain disorders, e.g., Parkinson’s disease (Lenz et al, 1994; Nini et al, 1995; Hammond et al, 2007), epilepsy (Wong et al, 1986; Schomer and Lopes da Silva, 2010), and tinnitus (Ochi and Eggermont, 1997; Llinas et al, 1999; Weisz et al, 2005; Eggermont and Tass, 2015). CRstimulation causes a desynchronization and in turn, due to STDP (Gerstner et al, 1996; Markram et al, 1997; Bi and Poo, 1998; Feldman, 2000), leads to a decrease of the mean synaptic weight In this way, CR stimulation shifts the neuronal network from a pathological attractor with up-regulated synchrony and connectivity to a physiological attractor with down-regulated synchrony and connectivity (Tass and Majtanik, 2006; Hauptmann and Tass, 2007; Popovych and Tass, 2012). In this way CR applied induces an unlearning of the abnormal synaptic connectivity and abnormal neuronal synchrony, so that an anti-kindling is achieved (Tass and Majtanik, 2006)
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