Abstract
Modulation of the rhythmic activity of local field potentials (LFP) in neuronal networks could be a mechanism of deep brain stimulation (DBS). However, exact changes of LFP during the periods of high-frequency stimulation (HFS) of DBS are unclear because of the interference of dense stimulation artifacts with high amplitudes. In the present study, we investigated LFP changes induced by HFS of afferent axons in the hippocampal CA1 region of urethane-anesthetized rats by using a proper algorithm of artifact removal. Afterward, the LFP changes in the frequency bands of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] rhythms were studied by power spectrum analysis and coherence analysis for the recorded signals collected in the pyramidal layer and in the stratum radiatum of CA1 region before, during and after 1-min long 100 and 200[Formula: see text]Hz HFS. Results showed that the power of LFP rhythms in higher-frequency band ([Formula: see text] rhythm) increased in the pyramidal layer and the power of LFP rhythms in lower-frequency bands ([Formula: see text], [Formula: see text] and [Formula: see text] rhythms) decreased in the stratum radiatum during HFS. The synchronization of [Formula: see text] rhythm decreased and the synchronization of [Formula: see text] rhythm increased during HFS in the stratum radiatum. These results suggest that axonal HFS could modulate LFP rhythms in the downstream brain areas with a plausible underlying mechanism of partial axonal blockage induced by HFS. The study provides new evidence to support the mechanism of DBS modulating rhythmic activity of neuronal populations.
Highlights
Deep brain stimulation (DBS) has been investigated widely in the treatment of various neurological disorders such as Parkinson's disease, epilepsy and Alzheimer'sThis is an Open Access article published by World Scientic Publishing Company
Because the large artifacts of stimulation pulses during high-frequency stimulation (HFS) trains would interfere with the analysis of LFP rhythms, a linear interpolation algorithm was used to remove the artifacts and to extract LFP signals submerged in the artifacts (Fig. 2)
The maximum values of jS À Rj/R out of the 5 rhythms were 0.13%, 0.26% and 0.51% for 100, 200 and 400 Hz HFS, respectively. These results indicate that the linear interpolation algorithm did not distort the LFP rhythms markedly even when the frequency of HFS was as high as 400 Hz
Summary
Deep brain stimulation (DBS) has been investigated widely in the treatment of various neurological disorders such as Parkinson's disease, epilepsy and Alzheimer's. This is an Open Access article published by World Scientic Publishing Company. Rhythmic activity of localeld potentials (LFP) could provide more relevant information of changes of neuronal networks associated with DBS (Kühn et al, 2005; Pogosyan et al, 2010; Lempka & McIntyre, 2013). It is plausible that modulating the neuronal rhythms of LFP could be a mechanism underlying the e±cacy of DBS (Karas et al, 2013; McIntyre et al, 2004b; Montgomery & Baker, 2000)
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