  Motivated by the fact that the pre-inflationary era may evolve in an exotic
way, in this work we formalize anisotropic evolution in the context of modified
gravity, focusing on pre-inflationary and near the vicinity of the inflationary
epochs. We specialize on specific metrics like Bianchi and Taub and we
formalize the inflationary theory in vacuum $F(R)$ gravity, in $F(R)$ gravity
with an extra scalar field and in Gauss-Bonnet gravity. We discuss the
qualitative effects of the anisotropies on the evolution of the Universe and
also we consider several specific solutions, like the de Sitter solution, in
both the isotropic and anisotropic contexts. Furthermore, several exotic
modified gravity cosmological solutions, like the ones which contain finite
time singularities, are also discussed in brief.
