title: Altered resting-state network connectivity in stroke patients with and without apraxia of speech.
abstract: Motor speech disorders, including apraxia of speech (AOS), account for over 50% of the communication disorders following stroke. Given its prevalence and impact, and the need to understand its neural mechanisms, we used resting state functional MRI to examine functional connectivity within a network of regions previously hypothesized as being associated with AOS (bilateral anterior insula (aINS), inferior frontal gyrus (IFG), and ventral premotor cortex (PM)) in a group of 32 left hemisphere stroke patients and 18 healthy, age-matched controls. Two expert clinicians rated severity of AOS, dysarthria and nonverbal oral apraxia of the patients. Fifteen individuals were categorized as AOS and 17 were AOS-absent. Comparison of connectivity in patients with and without AOS demonstrated that AOS patients had reduced connectivity between bilateral PM, and this reduction correlated with the severity of AOS impairment. In addition, AOS patients had negative connectivity between the left PM and right aINS and this effect decreased with increasing severity of non-verbal oral apraxia. These results highlight left PM involvement in AOS, begin to differentiate its neural mechanisms from those of other motor impairments following stroke, and help inform us of the neural mechanisms driving differences in speech motor planning and programming impairment following stroke.
authors.affiliation: Research Imaging Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
authors.forename: Anneliese B
authors.initials: AB
authors.lastname: New
authors.affiliation: Research Imaging Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA ; Department of Neurology, University of Texas Health Science Center San Antonio, San Antonio, TX, USA ; Joint Program in Biomedical Engineering, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA ; Honors College, University of Texas, San Antonio, TX, USA.
authors.forename: Donald A
authors.initials: DA
authors.lastname: Robin
authors.affiliation: Research Imaging Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA ; Department of Neurology, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Parkinson
authors.affiliation: Mayo Clinic, Rochester, MN, USA.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Duffy
authors.affiliation: University of Pittsburgh and Veterans Administration, Pittsburgh Healthcare System, Pittsburgh, PA, USA.
authors.forename: Malcom R
authors.initials: MR
authors.lastname: McNeil
authors.affiliation: Neuroscience Research Australia and University of New South Wales, Randwick, NSW,Australia.
authors.forename: Olivier
authors.initials: O
authors.lastname: Piguet
authors.affiliation: Neuroscience Research Australia and University of New South Wales, Randwick, NSW,Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Hornberger
authors.affiliation: Wellcome Trust Centre for Neuroimaging, University College London, London, UK.
authors.forename: Cathy J
authors.initials: CJ
authors.lastname: Price
authors.affiliation: Institute of Neuroscience and Medicine (INM-1), Research Center Julich, Julich, Germany ; Department of Clinical Neuroscience and Medical Psychology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
authors.forename: Simon B
authors.initials: SB
authors.lastname: Eickhoff
authors.affiliation: Neuroscience Research Australia and University of New South Wales, Randwick, NSW,Australia ; Faculty of Health Sciences, The University of Sydney, Sydney, Australia.
authors.forename: Kirrie J
authors.initials: KJ
authors.lastname: Ballard
mesh_terms: D000368:Aged; D001072:Apraxias / Q000209:etiology / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000503:physiopathology*; D063132:Connectome / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D020521:Stroke / Q000150:complications / Q000503:physiopathology*
keywords: Apraxia of speech; Network connectivity; Resting-state fMRI; Stroke