The availability of functional magnetic resonance imaging （fMRI） has revolutionized the study of language, especially figurative language such as metaphor comprehension. The last decade has witnessed considerable research on the neural mechanisms of metaphor comprehension at word, sentence, and discourse levels respectively. This paper offers a general review of fMRI investigations into the neural networks involved in metaphor processing to date. First we introduce how metaphor studies can be done by means of fMRI technique at word, sentence and discourse levels. Then we discuss several confounding factors such as familiarity, and task demand and difficulty, which may lead to inconsistent results in fMRI experiments. Finally, we try to propose some constructive suggestions for further research in this field.
