Automorphisms of central extensions of type I von Neumann algebras

Given a von Neumann algebra M we consider its central extension E(M). For type I von Neumann algebras, E(M) coincides with the algebra LS(M) of all locally measurable operators affiliated with M: In this case we show that an arbitrary automorphism T of E(M) can be decomposed as T = T_a ο T_φ where T_a(x) = axa^-1 is an inner automorphism implemented by an element a 2 ∈ (M), and T _φ is a special automorphism generated by an automorphism φ of the center of E(M): In particular if M is of type I_∞ then every band preserving automorphism of E(M) is inner.