title: Neural underpinnings for model-oriented therapy of aphasic word production.
abstract: Model-oriented therapies of aphasic word production have been shown to be effective, with item-specific therapy effects being larger than generalisation effects for untrained items. However, it remains unclear whether semantic versus phonological therapy lead to differential effects, depending on type of lexical impairment. Functional imaging studies revealed that mainly left-hemisphere, perisylvian brain areas were involved in successful therapy-induced recovery of aphasic word production. However, the neural underpinnings for model-oriented therapy effects have not received much attention yet. We aimed at identifying brain areas indicating (1) general therapy effects using a naming task measured by functional magnetic resonance imaging (fMRI) in 14 patients before and after a 4-week naming therapy, which comprised increasing semantic and phonological cueing-hierarchies. We also intended to reveal differential effects (2) of training versus generalisation, (3) of therapy methods, and (4) of type of impairment as assessed by the connectionist Dell model. Training effects were stronger than generalisation effects, even though both were significant. Furthermore, significant impairment-specific therapy effects were observed for patients with phonological disorders (P-patients). (1) Left inferior frontal gyrus, pars opercularis (IFGoper), was a positive predictor of therapy gains while the right caudate was a negative predictor. Moreover, less activation decrease due to therapy in left-hemisphere temporo-parietal language areas was positively correlated with therapy gains. (2) Naming of trained compared to untrained words yielded less activation decrease in left superior temporal gyrus (STG) and precuneus, bilateral thalamus, and right caudate due to therapy. (3) Differential therapy effects could be detected in the right superior parietal lobule for the semantic method, and in regions involving bilateral anterior and mid cingulate, right precuneus, and left middle/superior frontal gyrus for the phonological method. (4) Impairment-specific changes of activation were found for P-patients in left IFGoper. Patients with semantic disorders (S-patients) relied on right frontal areas involving IFG, pars triangularis. After therapy, they revealed less activation decrease in areas involving left STG, caudate, paracentral lobule, and right rolandic operculum. Regarding naming performance, the present study corroborates previous findings on training and generalisation effects and reveals differential therapy effects for P-patients. Moreover, brain imaging results confirm a predominance of (1) general effects in the left brain hemisphere. (2) Brain regions related to visual strategy, monitoring/feedback, and articulatory patterns were characteristic for the familiar trained items. (3) Distinct regions associated with strategies, monitoring capacities, and linguistic information indicate the specific therapeutic influence on word retrieval. (4) While P-patients relied more on preserved phonological functions in the left hemisphere, S-patients revealed right-sided compensation of semantic processing as well as increased strategic efforts in both hemispheres.
authors.affiliation: Section Neuropsychology, Department of Neurology, RWTH Aachen University, Aachen 52074, Germany; Clinical and Cognitive Neuroscience, Department of Neurology, RWTH Aachen University, Aachen, Germany; JARA-BRAIN, Aachen Juelich Research Alliance, Translational Brain Medicine, Aachen, Germany; SRH University of Applied Sciences Gera, Gera, Germany. Electronic address: sabel@ukaachen.de.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Abel
authors.affiliation: Department of Neurology, University Medical Centre Freiburg, Freiburg im Breisgau, Germany.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Weiller
authors.affiliation: Clinical and Cognitive Neuroscience, Department of Neurology, RWTH Aachen University, Aachen, Germany; JARA-BRAIN, Aachen Juelich Research Alliance, Translational Brain Medicine, Aachen, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Huber
authors.affiliation: Section Neuropsychology, Department of Neurology, RWTH Aachen University, Aachen 52074, Germany; JARA-BRAIN, Aachen Juelich Research Alliance, Translational Brain Medicine, Aachen, Germany; Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Aachen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Willmes
mesh_terms: D000328:Adult; D000368:Aged; D001037:Aphasia / Q000473:pathology / Q000534:rehabilitation*; D001521:Behavior Therapy / Q000379:methods*; D001921:Brain / Q000098:blood supply / Q000473:pathology; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009275:Names; D009949:Orientation; D010100:Oxygen / Q000097:blood; D012660:Semantics; D014825:Vocabulary
chemical_list: D010100:Oxygen
keywords: Aphasia; Naming; Phonology; Semantics; Treatment; fMRI