Flinker, A. et al. (2015). Redefining the role of Broca's area in speech. www.pnas.org/cgi/doi/10.1073/pnas.1414491112
The authors report one of their findings that when the motor cortex is activated during spoken responses, Broca’s area is "surprisingly silent". They provide additional information about activity of Broca's area - relative to motor cortex - depending upon the novelty of what is spoken.
The study used electrical recording from the cortical surface in a sample of seven participants who were to undergo neurosurgical treatment for refractory epilepsy.
The authors note that results were consistent to the presentation of patients with cortical lesions that are limited to Broca’s - it is typical for this presentation not to cause a Broca’s aphasia but to result in an acute, transient mutism.
The authors conclude that Broca's area might not be the historically defined 'seat of articulation' but may be "a key node" in the transformation of neural information as it is processed within comprehensive networks essential for speech production.
Please read the paper itself to get a full understanding of the methodology, results, and implications of this study.