Although the right hemisphere is capable of comprehending words, to what extent and
under what circumstances this contributes to normal natural language comprehension
has remained obscure. The positron emission tomography (PET) functional
neuroimaging experiment reported here showed that right hemisphere inferior frontal
gyrus and dorsolateral prefrontal cortex are activated while subjects read temporarily
ambiguous sentences in which the less preferred meaning of the word must finally be
chosen. This result demonstrates that the right hemisphere is indeed involved in normal
sentence comprehension under some circumstances. We relate this evidence to data from
right hemisphere damaged patients which suggests that the right hemisphere is involved
in revising meanings more generally and to neuroimaging evidence that the right frontal
lobe is active in verbal short-term memory tasks.