Brain functions are determined not only by processing in single brain areas but also by dynamic interactions within and between distributed neural networks. We investigated functional connectivity between two brain systems underlying complementary components of verbal working memory. The use of the articulatory rehearsal ("inner speech") mechanism enhanced neural activity in ventral premotor cortex and Broca's area. These activations showed a negative functional coupling with anatomically connected brain regions subserving the non-articulatory maintenance of phonological information, i.e. the "inner ear".