title: Effect of meaning on apraxic finger imitation deficits.
abstract: Apraxia typically results from left-hemispheric (LH), but also from right-hemispheric (RH) stroke, and often impairs gesture imitation. Especially in LH stroke, it is important to differentiate apraxia-induced gesture imitation deficits from those due to co-morbid aphasia and associated semantic deficits, possibly influencing the imitation of meaningful (MF) gestures. To explore this issue, we first investigated if the 10 supposedly meaningless (ML) gestures of a widely used finger imitation test really carry no meaning, or if the test also contains MF gestures, by asking healthy subjects (n=45) to classify these gestures as MF or ML. Most healthy subjects (98%) classified three of the 10 gestures as clearly MF. Only two gestures were considered predominantly ML. We next assessed how imitation in stroke patients (255 LH, 113 RH stroke) is influenced by gesture meaning and how aphasia influences imitation of LH stroke patients (n=208). All patients and especially patients with imitation deficits (17% of LH, 27% of RH stroke patients) imitated MF gestures significantly better than ML gestures. Importantly, meaningfulness-scores of all 10 gestures significantly predicted imitation scores of patients with imitation deficits. Furthermore, especially in LH stroke patients with imitation deficits, the severity of aphasia significantly influenced the imitation of MF, but not ML gestures. Our findings in a large patient cohort support current cognitive models of imitation and strongly suggest that ML gestures are particularly sensitive to detect imitation deficits while minimising confounding effects of aphasia which affect the imitation of MF gestures in LH stroke patients.
authors.affiliation: Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Jülich, Jülich 52428, Germany; Department of Neurology, University Hospital Cologne, Cologne, Germany. Electronic address: e.achilles@fz-juelich.de.
authors.forename: E I S
authors.initials: EIS
authors.lastname: Achilles
authors.affiliation: Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Jülich, Jülich 52428, Germany; Department of Neurology, University Hospital Cologne, Cologne, Germany.
authors.forename: G R
authors.initials: GR
authors.lastname: Fink
authors.affiliation: Division of Cognitive Sciences, University of Potsdam, Potsdam, Germany.
authors.forename: M H
authors.initials: MH
authors.lastname: Fischer
authors.affiliation: Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Jülich, Jülich 52428, Germany; Department of Neurology, University Hospital Cologne, Cologne, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Dovern
authors.affiliation: Department of Neurology, University Hospital Cologne, Cologne, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Held
authors.affiliation: Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Jülich, Jülich 52428, Germany.
authors.forename: D C
authors.initials: DC
authors.lastname: Timpert
authors.affiliation: Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Jülich, Jülich 52428, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Schroeter
authors.affiliation: Department of Neurology, Kliniken Schmieder Allensbach, Allensbach, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Schuetz
authors.affiliation: Department of Neurology, Kliniken Schmieder Allensbach, Allensbach, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Kloetzsch
authors.affiliation: Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Jülich, Jülich 52428, Germany; Department of Neurology, University Hospital Cologne, Cologne, Germany.
authors.forename: P H
authors.initials: PH
authors.lastname: Weiss
mesh_terms: D000368:Aged; D001072:Apraxias / Q000209:etiology / Q000523:psychology*; D005260:Female; D005385:Fingers; D005868:Gestures; D006801:Humans; D007100:Imitative Behavior; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000150:complications*
keywords: Apraxia; Cognitive models of imitation; Meaning