title: The Dual-Loop Model and the Human Mirror Neuron System: an Exploratory Combined fMRI and DTI Study of the Inferior Frontal Gyrus.
abstract: The inferior frontal gyrus (IFG) is active during both goal-directed action and while observing the same motor act, leading to the idea that also the meaning of a motor act (action understanding) is represented in this "mirror neuron system" (MNS). However, in the dual-loop model, based on dorsal and ventral visual streams, the MNS is thought to be a function of the dorsal steam, projecting to pars opercularis (BA44) of IFG, while recent studies suggest that conceptual meaning and semantic analysis are a function of ventral connections, projecting mainly to pars triangularis (BA45) of IFG. To resolve this discrepancy, we investigated action observation (AO) and imitation (IMI) using fMRI in a large group of subjects. A grasping task (GR) assessed the contribution from movement without AO. We analyzed connections of the MNS-related areas within IFG with postrolandic areas with the use of activation-based DTI. We found that action observation with imitation are mainly a function of the dorsal stream centered on dorsal part of BA44, but also involve BA45, which is dorsally and ventrally connected to the same postrolandic regions. The current finding suggests that BA45 is the crucial part where the MNS and the dual-loop system interact.
authors.affiliation: Section of Neurological Rehabilitation, Hans Berger Department of Neurology Department of Neurology, Moritz Klinik Bad Klosterlausnitz, Bad Klosterlausnitz, Germany Center for Sepsis Control and Care (CSCC), Jena University Hospital, Jena, Germany.
authors.forename: Farsin
authors.initials: F
authors.lastname: Hamzei
authors.affiliation: Department of Neurology.
authors.forename: Magnus-Sebastian
authors.initials: MS
authors.lastname: Vry
authors.affiliation: Department of Neurology, University Clinic of Leipzig, Germany.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Saur
authors.affiliation: Department of Neurology.
authors.forename: Volkmar
authors.initials: V
authors.lastname: Glauche
authors.affiliation: Department of Neurology.
authors.forename: Markus
authors.initials: M
authors.lastname: Hoeren
authors.affiliation: Department of Neuroradiology, University Clinic of Freiburg, Germany.
authors.forename: Irina
authors.initials: I
authors.lastname: Mader
authors.affiliation: Department of Neurology.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Weiller
authors.affiliation: Department of Neurology.
authors.forename: Michel
authors.initials: M
authors.lastname: Rijntjes
mesh_terms: D000328:Adult; D001931:Brain Mapping; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007100:Imitative Behavior; D008279:Magnetic Resonance Imaging; D008297:Male; D059167:Mirror Neurons / Q000502:physiology*; D008959:Models, Neurological; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D017397:Prefrontal Cortex / Q000033:anatomy & histology / Q000502:physiology*; D011597:Psychomotor Performance; D012660:Semantics; D055815:Young Adult
keywords: DTI; action observation; dorsal and ventral stream; fMRI; mirror neuron system