With only a reduction in directedness, relative to cells in the presence of EGFR signaling. This suggests that EGFR signaling predominantly impacts the velocity and to a lesser extent the directedness �C of SE NPC galvanotaxis. Further, the migratory behaviour of NPCs exposed to a dcEF in the absence of EGF was not significantly different from that of NPCs in the presence of erlotinib. Taken together, these data suggest that while EGF signaling plays a role in the galvanotactic response of NPCs, it is not responsible for all the cell behaviours observed. We have demonstrated that clonally-derived pure populations of adult SE-derived NPCs exhibit rapid and directed galvanotaxis toward the cathode of a dcEF. Moreover, we have shown this phenomenon to be unique to undifferentiated NPCs; inducing their maturation into differentiated phenotypes is associated with a loss of electrically-induced migratory capacity. Through continuous fresh media cross-perfusion experiments, we show that directed migration of NPCs in the presence of an applied dcEF is a direct effect of the field rather than an indirect chemotactic effect. We have provided evidence that NPC galvanotaxis is moderated by EGF signaling; both the removal of EGF from the culture medium as well as the blockade of EGFR via erlotinib significantly attenuate NPC galvanotaxis. Most interesting is the finding that loss of galvanotactic behaviour associated with FBSinduced maturation of NPCs could not be reversed by replacing the cells in the presence of EGF and bFGF. Thus our data indicate externally applied dcEFs can stimulate and guide the migration of undifferentiated SE NPCs, but not that of NPCs induced to differentiate into mature neural phenotypes. The role of electric fields in the central nervous system has been previously explored. The axons of embryonic rat hippocampal neurons align perpendicular to the direction of an applied dcEF in an EF strength-dependent manner after 24 hours of exposure, and interestingly, individual growth cones of dendrites, but not axons, undergo cathodal orientation. Xenopus embryo neural tube cells have been shown to elicit EF strength-dependent cathodal turning of neurites, although the direction of neurite growth in response to an applied dcEF varies depending on the substrate adhesiveness and net surface charge; negatively charged substrates such as laminin promote cathodal outgrowth, whereas positively charged substrates such as lysine promote anodal outgrowth, reviewed in. dcEFs also serve to modulate neuronal structure through differential neurite growth rate regulation, and by enhancing neurite branching. Interestingly, electric field AbMole Halothane exposure has been reported to impact the differentiation profile of NPCs. In higher strength dcEFs adult rat hippocampal NPCs exhibit a tendency to differentiate into neurons, whereas the differentiation profile of embryonic mouse NPCs encapsulated in alginate hydrogel beads and exposed to lower-strength alternating current EFs is dependent on the frequency and duration of stimulation. While these studies investigated the neurite response or differentiation of relatively stationary somata in the presence of a dcEF, we were interested in the entire cell body translocation of NPCs. The findings reported here are similar to those of a recent study, in which they showed that NPCs derived from an adult rat hippocampal cell line, as well as embryonic rat NPCs, undergo enhanced speed and cathodal directedness of migration.