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 (M1 TeV), the inflaton field must be extremely light. This problem may disappear in models with an intermediate (M10^11 GeV) to high (M10^16 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.