PET studies of language: An assessment of the reliability of the technique

In order to understand the basis of language in the brain, we must be able to describe the neurological systems that are used in language comprehension and production. In this paper, one technique for functional neuroimaging is discussed: measurement of blood flow change using positron emission tomography (PET). Two experiments were carried out investigating the usefulness of this method. One experiment examined the intrinsic time limitations of blood flow change as a measure of cognitive activity. A second issue considered is the replicability of the results obtained using this method. A comparison of two experiments containing the same conditions suggests that the results are replicable, when the experiments and method are similar. One case is discussed where the experiments differ; it is suggested that this is due to a difference in the materials used in the experiments, and that the difference has a principled basis.