It is a central issue in cognitive neuroscience whether language ability is specialized in the human brain. In the September 12 issue of Neuron, HFSP Young Investigator Kuniyoshi L. Sakai and colleagues reported that transcranial magnetic stimulation to the left inferior frontal gyrus (red; Broca's area) results in selective priming effects on syntactic decisions (letters on the black background; 'yuki-wo tsumoru' [Someone lies snow]), but not on semantic decisions (letters on the gray background; 'yuki-wo shikaru' [Someone scolds snow]). This effect is observed at a specific timing and location, as the stimulation to the left middle frontal gyrus (green) has no significant effect. An MRI map of a standard brain is superimposed on a drawing of the early 1800s used in phrenology for functional localization. These results provide the direct evidence of the involvement of Broca's area in syntactic processing.
Reference: Sakai, K. L., et al.
"Selective priming of syntactic processing by event-related transcranial magnetic stimulation of Broca's area."
Neuron, 35, 1177-1182 (2002).