A comparison of functional MR activation patterns during silent and audible language tasks

PURPOSE: To compare word generation tasks performed silently and aloud as paradigms for functional MR. METHODS: Images were obtained at 1.5 T, with echoplanar acquisition in nine subjects performing word generation aloud or silently. Functional images created from the echoplanar images by means of cross-correlation techniques were superimposed on anatomic reference images. The location of activation from the two tasks was tabulated; the number of activated pixels in each region from the two tasks was compared. RESULTS: Both silent and aloud word generation produced activation in the inferior frontal lobes, sensorimotor cortex regions, supplementary motor areas, and anterior cingulate gyri, predominantly in the dominant hemisphere. Significantly more activated pixels and fewer artifacts were detected with silent word generation than with word generation aloud. CONCLUSION: Word generation silently or aloud produce activation in the brain. Greater activation can be detected in the left frontal lobe with silent word generation, although the subject's performance of the task cannot be monitored independently during silent word generation.