SPP1 and Stroke: Anodal tDCS enhanced expression of several genes coding for MHC-I, affecting inflammation and synaptic plasticity, while cathodal tDCS increased expression of the gene encoding for the immunoregulatory protein OPN linking tDCS treatment to beneficial effects on regeneration after stroke or cerebral hemorrhage (Yan et al., 2009; Wu et al., 2011; Rabenstein et al., 2015; Ladwig et al., 2017; Rogall et al., 2018).