Figure 6: The average time course of signal intensity changes over subjects in Broca’s area and its right-hemisphere homologue obtained from the ROI analysis during speaking a letter name silently and overtly (top), and during generating an animal name silently and overtly (bottom). Overtly speaking a letter name increased activity in Broca’s area but decreased activity in Broca’s right homologue, compared with silently speaking a letter name (top). Conversely, overtly generating an animal name decreased activity in both Broca’s area and its right homologue (bottom). Note that the magnitudes of the BOLD signal changes were smaller and their rise and fall more sharply peaked during overt animal-name generation, compared with during silent animal-name generation (bottom). The ROI masks were generated from the most activated clusters, which were in the silent conditions. L:left; R: right.