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Poster C17, Thursday, November 9, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Lesion Sites Associated with Apraxia of Speech: Report of a new case and implications for Neural Models of Speech Production

Venugopal Balasuramanian1, Ludo Max2;1Seton Hall University,NJ, 2University of Washington,Seattle

Introduction Luria (1966, 1970) proposed a category of afferent apraxic motor aphasia (AAMA) to account for the speech symptoms in cases with left hemisphere (LH) parietal lobe damage. According to Luria, the difficulty in speech articulation in such cases was in finding the appropriate articulatory movements for the production of individual sounds, and sound sequences, accompanied by positional apraxia of the speech organs. Thus, Luria’s description of AAMA matches the contemporary definition of AOS but with an emphasis on the pivotal role of parietal lobe lesion. This point of view provides an important addition to the common perspective reflected in the Directions Into Velocities of Articulators (DIVA) model that AOS accompanies lesions in the left posterior inferior frontal gyrus and the premotor cortex, the site that stores speech sound maps (Guenther & Hickok, 2016). In the DIVA model, the parietal cortex of both hemispheres constitutes the neural substrate for the somato-sensory feedback circuit. Here, we report on a case with apraxia of speech (AOS) resulting from parietal lesion and we discuss implications for the role of the parietal lobe in apraxia of speech. Methods Subject. RL, a 58-year-old right-handed male high school graduate, had a stroke-induced lesion in the left mid parietal region (see Figure 1.). Procedure. Clinical evaluation one month post-onset consisted of the use of Minnesota Test for Differential Diagnosis of Aphasia (MTDDA), Apraxia Battery for Adults (ABA), and Boston Naming Test (BNT). At one year post-onset, RL ‘s speech was evaluated by administering ABA, BNT, and Boston Diagnostic Aphasia Examination (BDAE). Two additional tasks, namely, Oral reading of the Grandfather’s passage, and spontaneous responsive speech elicited by the question “Tell me about the first job you ever had” were employed to gather additional data on speech production. Results RL’s speech disruptions during spontaneous speech primarily included 20 part-word repetition (PWR), 10 whole word repetitions (WWR), 10 single interjections (SI), 14 repeated interjections (RI), and 1 sound prolongation (SP). During the reading of the Grandfather Passage RL produced 26 (PWR), 11 (WWR), 22 (RI), and one sound prolongation (SP). On the reading task, RL used seven types of phonological processes that altered the segmental characteristics of the target words. The types and frequency of occurrence of each type of process were as follows: six vowel changes (VC), five initial consonant deletions (ICD), five final consonant deletions (FCD), four cluster reductions (CR), two frontings (FR), two backings (BK), and two stoppings (ST). RL’s spontaneous speech also evidenced such production simplifications. Discussion RL’s simplification and positional apraxia of the lips and tongue suggest the involvement of both phonological as well as phonetic encoding deficits. (Galluzzi et al, 2015; Wolk, 1984).The current study provides additional empirical evidence for the possibility that multiple sites of lesions may be associated with AOS (Hickok et al, 2014). Luria’s conceptualization of AAMA neatly accounts for RL’s symptom profile.

Topic Area: Language Development

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