Characterizing Articulation in Apraxic Speech Using Real-Time Magnetic Resonance Imaging.
Real-time magnetic resonance imaging (MRI) and accompanying analytical methods are shown to capture and quantify salient aspects of apraxic speech, substantiating and expanding upon evidence provided by clinical observation and acoustic and kinematic data. Analysis of apraxic speech errors within a dynamic systems framework is provided and the nature of pathomechanisms of apraxic speech discussed.



One adult male speaker with apraxia of speech was imaged using real-time MRI while producing spontaneous speech, repeated naming tasks, and self-paced repetition of word pairs designed to elicit speech errors. Articulatory data were analyzed, and speech errors were detected using time series reflecting articulatory activity in regions of interest.



Real-time MRI captured two types of apraxic gestural intrusion errors in a word pair repetition task. Gestural intrusion errors in nonrepetitive speech, multiple silent initiation gestures at the onset of speech, and covert (unphonated) articulation of entire monosyllabic words were also captured.



Real-time MRI and accompanying analytical methods capture and quantify many features of apraxic speech that have been previously observed using other modalities while offering high spatial resolution. This patient's apraxia of speech affected the ability to select only the appropriate vocal tract gestures for a target utterance, suppressing others, and to coordinate them in time.
University of Southern California, Los Angeles.
Christina
C
Hagedorn
Macquarie University, North Ryde, New South Wales, Australia.
Michael
M
Proctor
University of Southern California, Los Angeles.
Louis
L
Goldstein
University of Arizona, Tucson.
Stephen M
SM
Wilson
University of California, San Francisco.
Bruce
B
Miller
University of California, San Francisco.
Maria Luisa
ML
Gorno-Tempini
University of Southern California, Los Angeles.
Shrikanth S
SS
Narayanan
D001072:Apraxias / Q000000981:diagnostic imaging*; D001921:Brain / Q000000981:diagnostic imaging; D005868:Gestures; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D009048:Motor Skills; D009055:Mouth / Q000000981:diagnostic imaging*; D010865:Pilot Projects; D057178:Primary Progressive Nonfluent Aphasia / Q000000981:diagnostic imaging; D013018:Sound Spectrography; D013060:Speech; D013068:Speech Production Measurement / Q000379:methods*; D013997:Time Factors