The effects of anodal transcranial direct current stimulation on cortical spreading depression
Cherukuri, Sahitya Priya
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Cortical spreading depression (CSD) is a depolarizing wave that travels through the cerebral cortex, and is followed by an inhibition of cortical activity. The propagation of CSD elicits metabolic challenges in tissue that may be irrecoverable in an ischemic brain, and thus has implications in neurological disease. Limiting the incidence of CSD may be instrumental in limiting the extent of neuronal damage following brain injury. Transcranial direct current stimulation (tDCS) is a form of brain stimulation that alters the level of cortical activity. Anodal tDCS, which increases cortical excitability, is used to treat a variety of neurological syndromes but may have the potential to exacerbate certain pathologies. This contention has never been evaluated using in vivo brain recordings. This study seeks to determine the effects of anodal tDCS on CSD, a phenomenon common to many neurological disorders. CSD was induced in the rat cortex by administration of potassium chloride. Animals were subjected to either anodal tDCS or sham stimulation. Cortical electrical activity was monitored using an intracortical multielectrode array, and data was analyzed to measure the effects of anodal tDCS versus sham on CSD incidence, velocity, amplitude, and several other characteristics of the wave. The hypothesis of the study was that anodal tDCS would increase the incidence, velocity, and amplitude of the CSD wave. No significant effects of anodal tDCS on CSD were observed in this study. Results indicate that anodal tDCS does not increase the velocity, amplitude, or frequency of the spreading depression wave, nor does it interrupt the wave. These data have implications for the use of anodal tDCS in the treatment of neurological disorders associated with spreading depression.