Effects of cathodal transcranial direct current stimulation on cortical spreading depression
Zamora, Francis Carolina
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The purpose of this study was to examine the effects of cathodal transcranial direct current stimulation (tDCS) on cortical spreading depression (CSD) in the rat cerebral cortex. CSD is a propagating wave of hyperexcitability that occurs in a number of neurological disorders characterized by excess cerebral excitability such as migraine, acute brain injury, or stroke. Since tDCS is a non-invasive method capable of inducing polarity-dependent changes in cortical excitability, we hypothesized that cathodal stimulation would prevent, attenuate, or change the characteristics of CSD. Forty Sprague-Dawley male rats were randomly divided into two stimulation condition groups: sham tDCS and cathodal tDCS. In both experimental groups, CSD was induced by applying potassium chloride onto cortical surface. Electroencephalogram (EEG) data was recorded during each experiment and subjected to analysis. CSD incidence was compared between the sham and cathodal tDCS group. We observed that significantly fewer CSD events were exhibited during cathodal tDCS relative to sham stimulation. Evaluation of CSD wave characteristics between experimental groups revealed no differences in propagation velocity, amplitude, or waveform of CSD, nor in the presence of neuronal silencing. The results of this study lend support for the use of cathodal tDCS as an effective method for reducing cortical excitability and provides the groundwork for future study of the mechanisms of tDCS and its treatment targets in neurological disorders whose symptoms are created or exacerbated by CSD.