Broca’s area is jointly activated during speech and gesture production

Despite the frequent suggestion in the literature that Broca's area is a common link between vocal and gestural models of the origins of language, this has never been established within a single motor-production study. In the present functional MRI experiment, participants were asked to describe the spatial properties of objects (e.g. a motorcycle) using speech, pantomime, and drawing. Pairwise conjunction analyses revealed that the left inferior gyrus - in combination with the left basal ganglia and ventral anterior thalamus - was jointly activated for the production of speech and pantomime but not for the conjunctions with drawing. Drawing and pantomime instead showed strong overlap in the intraparietal sulcus and superior parietal region bilaterally. These results provide the first demonstration in a production study that Broca's area is jointly activated by speech and gesture when depicting the same semantic content.