[en] We propose a generalization of the collective field theory hamiltonian, including interactions between the original bosonic collective field w₀(z) and supplementary fields anti w_j(z) realizing classically a w_∞ algebra. The latter are then shown to represent a 3-dimensional topological field theory. This generalization follows from a conjectured representation of the W_1+∞ algebra of bilinear fermion operators underlying the original matrix model. It provides an improved bosonization scheme for (1+1)-dimensional fermion theories. (orig.)