  We investigate a cosmological solution within the framework of a 5D standing
wave braneworld model generated by gravity coupled to a massless scalar
phantom-like field. By obtaining a full exact solution of the model we found a
novel dynamical mechanism in which the anisotropic nature of the primordial
metric gives rise to i) inflation along certain spatial dimensions, and ii)
deflation and a shrinking reduction of the number of spatial dimensions along
other directions. This dynamical mechanism can be relevant for dimensional
reduction in string and other higher dimensional theories in the attempt of
getting a 4D isotropic expanding space-time.
