title: The mirror neuron system and the strange case of Broca's area.
abstract: Mirror neurons, originally described in the monkey premotor area F5, are embedded in a frontoparietal network for action execution and observation. A similar Mirror Neuron System (MNS) exists in humans, including precentral gyrus, inferior parietal lobule, and superior temporal sulcus. Controversial is the inclusion of Broca's area, as homologous to F5, a relevant issue in light of the mirror hypothesis of language evolution, which postulates a key role of Broca's area in action/speech perception/production. We assess "mirror" properties of this area by combining neuroimaging and intraoperative neurophysiological techniques. Our results show that Broca's area is minimally involved in action observation and has no motor output on hand or phonoarticulatory muscles, challenging its inclusion in the MNS. The presence of these functions in premotor BA6 makes this area the likely homologue of F5 suggesting that the MNS may be involved in the representation of articulatory rather than semantic components of speech.
authors.affiliation: Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milano, Italy; Humanitas Clinical and Research Center, Rozzano, Milano, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Cerri
authors.forename: Monia
authors.initials: M
authors.lastname: Cabinio
authors.forename: Valeria
authors.initials: V
authors.lastname: Blasi
authors.forename: Paola
authors.initials: P
authors.lastname: Borroni
authors.forename: Antonella
authors.initials: A
authors.lastname: Iadanza
authors.forename: Enrica
authors.initials: E
authors.lastname: Fava
authors.forename: Luca
authors.initials: L
authors.lastname: Fornia
authors.forename: Valentina
authors.initials: V
authors.lastname: Ferpozzi
authors.forename: Marco
authors.initials: M
authors.lastname: Riva
authors.forename: Alessandra
authors.initials: A
authors.lastname: Casarotti
authors.forename: Filippo
authors.initials: F
authors.lastname: Martinelli Boneschi
authors.forename: Andrea
authors.initials: A
authors.lastname: Falini
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bello
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery*; D065711:Broca Area / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000502:physiology* / Q000601:surgery; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059167:Mirror Neurons / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D055815:Young Adult
keywords: Broca's area; functional magnetic resonance imaging; intraoperative brain mapping; language; mirror neurons; motor control