Inflation and large internal dimensions

We consider some aspects of inflation in models with large internal dimensions. If inflation occurs on a 3D wall after the stabilization of internal dimensions in the models with low unification scale (M~1 TeV), the inflaton field must be extremely light. This problem may disappear in models with an intermediate (M~10¹¹ GeV) to high (M~10¹⁶ GeV) unification scale. However, in all of these cases the wall inflation does not provide a complete solution to the horizon and flatness problems. To solve them, there must be a stage of inflation in the bulk before the compactification of internal dimensions.