The temporal characteristics of functional activation in Broca's area during overt picture naming.

The opercular and triangular sections of the inferior frontal gyrus, also known as Broca's area, have been shown to be involved in various language tasks. In the current study we investigated both the functional role, as well as the precise temporal involvement of Broca's area during picture naming. We applied online event-related transcranial magnetic stimulation (TMS) to Broca's area at five different time points after picture presentation, aiming to cover the complete language production process. Applying real TMS at 300 msec after picture presentation led to an increase in picture naming latency, whereas sham stimulation and real stimulation at earlier and later time windows did not result in any changes in reaction time (RT). Our methodological approach enabled us to get insight into the temporal characteristics of the involvement of this brain area during picture naming. Making use of this information and directly relating it to psycholinguistic models, we conclude that Broca's area may be involved in the process of syllabification during overt speech production.