Naming multiple objects: neural correlates as measured by positron emission tomography.

The aim of this study was to examine the neural substrates of multi-object naming by positron emission tomography in normals. Multi-object naming is used in a technique called contextual priming (CP) to elicit contextual effects on picture naming through systematic manipulation of the relatedness of to-be-named pictures in an array. Inhibitory and facilitatory effects of CP on naming have been used both to highlight the inner dynamics of the normal word retrieval system and to treat naming difficulties caused by acquired anomia. Because of the complexity of the CP technique, it is unclear whether it merely reflects lexical retrieval or whether it also recruits general cognitive resources such as attentional control and response selection to a significant degree. When compared with a baseline situation in which colored circles were named, multi-object naming elicited increased blood flow in the occipital lobe and in the left inferior temporal and fusiform gyri. These areas have been related to visual pattern recognition and semantic access, and the pattern of activation is in line with previous functional imaging studies on single picture naming. In conclusion, multi-object naming does not appear to activate brain regions beyond those needed for single object naming. These findings thus provide independent evidence for the claim that CP is a valid paradigm for the study of word production proper.