Exploring the Neural Substrates of Phonological Recovery for Symposium: Neural Correlates of Recovery and Rehabilitation

Abstract

Event Abstract Back to Event Exploring the Neural Substrates of Phonological Recovery for Symposium: Neural Correlates of Recovery and Rehabilitation Pelagie M. Beeson1*, Kindle Rising1, Andrew T. DeMarco1 and Steven Z. Rapcsak1, 2 1 University of Arizona, Speech, Language, and Hearing Sciences, United States 2 Southern Arizona Veteran's Administration Health Care System, Neurology, United States Background Phonological alexia and agraphia are written language disorders characterized by disproportionate difficulty processing nonwords compared to real words, giving rise to an exaggerated lexicality effect in reading and spelling1-5. Lesion-deficit studies demonstrate that phonological alexia/agraphia are associated with left perisylvian damage resulting in a central phonological deficit that disrupts sublexical processing of sounds and associated graphemes. The writing impairment is typically more severe and persistent than the reading deficit due to increased task demands6. Some individuals with phonological impairment have concomitant lexical-semantic deficits resulting in global agraphia manifested by poor spelling of both real or nonwords. Behavioral treatment can strengthen phonological skills and improve written language7, but response to treatment varies. Here we examined treatment outcomes in a large cohort of patients to explore the relationship between phonological recovery and lesion location. Method Forty-one individuals with left hemisphere damage were evaluated and provided treatment to improve written spelling: 23 presented with global agraphia; another 18 had phonological agraphia. High-resolution brain scans were acquired and precise 3D lesion maps were generated following procedures outlined in Andersen, Rapcsak, & Beeson (2010) 8. Three treatment protocols were implemented as indicated by initial performance, and whenever possible, participants advanced to the next treatment in the sequence. Lexical spelling treatment strengthens item-specific orthographic representations for words. Individuals with global agraphia begin with this treatment, and trained items are used as “key words” to assist in retrieval of sound-letter correspondences during phonological treatment. Phonological treatment strengthens sound-letter correspondences and phonological manipulation skills for individuals with phonological agraphia and those with global agraphia who advance from lexical treatment. Interactive treatment follows phonological treatment. A problem-solving approach is trained to promote use of residual or retrained lexical and phonological knowledge to improve spelling. Results All individuals with global agraphia successfully completed lexical treatment and proceeded to phonological treatment. They mastered retraining of sound-letter and letter-sound conversions for consonants, but 10 of 25 were not able to meet criterion on all stages of phonological treatment and did not advance to interactive treatment. Thirteen individuals with global agraphia and 18 with phonological agraphia progressed through all components of phonological and interactive treatment. Figure 1 illustrates lesion overlays by outcome groups (low global, high global, phonological), with relevant pre-post treatment performances. Groups completing phonological and interactive treatment made significant improvements on phonological transcoding and manipulation tasks, and generalized improvement reading and spelling words and nonwords. Such improvements were not significant for the low global group. Analysis of brain damage relative to treatment gains on nonword spelling revealed that whereas frontal damage was common, the low global group had greater concomitant damage to superior temporal gyrus and sulcus (see Figure). Conclusions All participants improved written language abilities in response to treatment, but one subgroup was limited in their ability to regain phonological skills. Both anterior and posterior components of the perisylvian phonological network were damaged in that group. These findings are consistent with fMRI activation when healthy adults write nonwords, and provide insight regarding neural support necessary for phonological rehabilitation. Figure 1 Acknowledgements This work was supported by grant R01-DC007646 from the National Institute on Deafness and Other Communication Disorders.