[en] The understanding of the turbulence-driven transport and the improved confinement (transport barriers) is the key issue in fusion research. Many kinds of the improved confinement mode in the core plasma of toroidal helical plasmas have been reported; e.g., the electron Internal Transport Barrier (e-ITB) with the strong positive radial electric field. The radial transition of the electric field was predicted to induce the internal transport barrier due to the shear of the radial electric field in the helical plasmas. The transition of the radial electric field was found on the Compact Helical System (CHS), and the improvement of confinement was found inside of the transition point for the radial electric field. In the previous study of the e-ITB, we have shown the reduction of the heat diffusivity because of the effect of zonal flows, which qualitatively predicts the e-ITB experimentally observed in the whole region of the strong positive electric field. On the other hand, the Internal Diffusion Barrier (IDB) in Large Helical Device (LHD) was recently discovered with the strong gradient of the density in a super dense core (SDC) plasma when a series of the pellet is injected. In this article, we present the unified transport model to explain the e-ITB and the IDB. At first, we examine the parameter regime in which the formation of the e-ITB can be predicted in helical plasmas with the effect of zonal flows. Next, the theoretical model for the IDB observed in LHD is shown. The mechanism, which is based on the transport reduction due to the shear of the radial electric field, is newly examined in the formation of the IDB. In the case of the particle fueling, the density rapidly increases. Therefore, the ion temperature temporally decreases and the positive gradient of the ion temperature is found to appear. From the ambipolar condition to determine the radial electric field profile, the positive electric field is found. As the result, the strong gradient of the electric field and the reduction of the anomalous particle diffusivity can be shown. When we study the physics of the transport barrier, the investigation of the density limit including the radiation loss for the case of the IDB in LHD is necessary. We discuss the critical density for the thermal stability in the case of the IDB in helical toroidal plasmas. (author)