title: Left inferior parietal dominance in gesture imitation: an fMRI study.
abstract: The inability to imitate gestures is an essential feature of apraxia. However, discrepancies exist between clinical studies in apraxic patients and neuroimaging findings on imitation. We therefore aimed to investigate: (1) which areas are recruited during imitation under conditions similar to clinical tests for apraxic deficits; (2) whether there are common lateralized areas subserving imitation irrespective of the acting limb side; and also (3) whether there are differences between hand and finger gestures. We used fMRI in 12 healthy, right handed subjects to investigate the imitation of four types of variable gestures that were presented by video clips (16 different finger and 16 different hand gestures with either the right or the left arm). The respective control conditions consisted of stereotyped gestures (only two gestures presented in pseudorandom order). Subtraction analysis of each type of gesture imitation (variable>stereotyped) revealed a bilateral activation pattern including the inferior parietal cortex Brodmann Area (BA 40), the superior parietal cortex, the inferior frontal cortex (opercular region), the prefrontal motor cortex, the lateral occipito-temporal junction, and the cerebellum. These results were supported by statistical conjunction of all four subtraction analyses and by the common analysis of all four types of gesture imitation. The direct comparison of the right and left hemispheric activation revealed a lateralization to the left only of the inferior parietal cortex. Comparisons between different types of gesture imitation yielded no significant results. In conclusion, gesture imitation recruits bilateral fronto-parietal regions, with significant lateralization of only one area, namely the left inferior parietal cortex. These in vivo data indicate left inferior parietal dominance for gesture imitation in right handers, confirming lesion-based theories of apraxia.
authors.affiliation: Neurologische Klinik Rechts der Isar, Technische Universität München, Munich, Germany. m.muehlau@neuro.med.tu-muenchen.de
authors.forename: Mark
authors.initials: M
authors.lastname: Mühlau
authors.forename: Joachim
authors.initials: J
authors.lastname: Hermsdörfer
authors.forename: Georg
authors.initials: G
authors.lastname: Goldenberg
authors.forename: Afra M
authors.initials: AM
authors.lastname: Wohlschläger
authors.forename: Florian
authors.initials: F
authors.lastname: Castrop
authors.forename: Robert
authors.initials: R
authors.lastname: Stahl
authors.forename: Michael
authors.initials: M
authors.lastname: Röttinger
authors.forename: Peter
authors.initials: P
authors.lastname: Erhard
authors.forename: Bernhard
authors.initials: B
authors.lastname: Haslinger
authors.forename: Andres O
authors.initials: AO
authors.lastname: Ceballos-Baumann
authors.forename: Bastian
authors.initials: B
authors.lastname: Conrad
authors.forename: Henning
authors.initials: H
authors.lastname: Boecker
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D002531:Cerebellum / Q000502:physiology; D004292:Dominance, Cerebral / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000502:physiology; D005625:Frontal Lobe / Q000502:physiology; D005868:Gestures; D006225:Hand / Q000502:physiology; D006801:Humans; D007100:Imitative Behavior / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009778:Occipital Lobe / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology*; D012016:Reference Values; D013702:Temporal Lobe / Q000502:physiology