  Current theories of language recovery after stroke are limited by a reliance
on small studies. Here, we aimed to test predictions of current theory and
resolve inconsistencies regarding right hemispheric contributions to long-term
recovery. We first defined the canonical semantic network in 43 healthy
controls. Then, in a group of 43 patients with chronic post-stroke aphasia, we
tested whether activity in this network predicted performance on measures of
semantic comprehension, naming, and fluency while controlling for lesion volume
effects. Canonical network activation accounted for 22-33% of the variance in
language test scores. Whole-brain analyses corroborated these findings, and
revealed a core set of regions showing positive relationships to all language
measures. We next evaluated the relationship between activation magnitudes in
left and right hemispheric portions of the network, and how right hemispheric
activation related to the extent of left hemispheric damage. Activation
magnitudes in the each hemispheric network were strongly correlated, but four
right frontal regions showed heightened activity in patients with large
lesions. Activity in two of these regions (inferior frontal gyrus pars
opercularis and supplementary motor area) was associated with better language
abilities in patients with larger lesions, but poorer language abilities in
patients with smaller lesions. Our results indicate that bilateral language
networks support language processing after stroke, and that right hemispheric
activations related to extensive left hemisphere damage occur outside of the
canonical semantic network and differentially contribute to in their
relationship to behavior depending on the extent of left hemispheric damage
