Article
Cathodal transcranial direct current stimulation induces regional, long-lasting, reversible reductions of cortical blood perfusion in rats
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Published: | June 4, 2012 |
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Objective: Transcranial direct current stimulation (tDCS) induces polarity-specific changes of cerebral blood flow (CBF). To determine whether these changes are focally limited or if they incorporate large cortical regions with the potential for therapeutic applicability, we investigated the effects of cathodal tDCS on CBF in an established tDCS rat model with particular attention to the spatial extension in CBF changes using laser Doppler blood perfusion imaging (LDI).
Methods: Twenty Sprague Dawley rats received one single 15-minute session of cathodal tDCS at current intensities of 200, 400, 600 or 700 uA applied over electrode contact areas (ECA) of 3.5, 7.0, 10.5 or 14.0 mm2. CBF was measured prior and after tDCS with LDI in three defined regions of interest (ROI) over the stimulated left hemisphere (region anterior to ECA - ROI 1, ECA - ROI 2, region posterior to ECA - ROI 3).
Results: A regional decrease in CBF was measured after cathodal tDCS, the extent of the decrease depending on the current density applied. The most effective and spatially limited reduction in CBF (up to 50%, that lasted as long as 90 min) was found after the application of 600 uA over an ECA of 10.5 mm2. This significant reduction in CBF even lasted up to 90 minutes in distant cortical areas (ROI 1 and 3) that were not directly related to the ECA (ROI 2).
Conclusions: Cathodal tDCS induces a regional, long-lasting, reversible decrease in CBF that is not limited to the region to which tDCS is applied. These findings underline the possible potential of tDCS to modulate ischemic tolerance and to reduce ischemic neuronal damage in acute stroke or vasospasm.