Adult Brain Plasticity Elicited by Anomia Treatment

Abstract

Abstract& We describe a study where a specific treatment method for word-finding difficulty (so-called contextual priming technique, which combines massive repetition priming with semantic priming) was applied with three chronic left hemispheredamaged aphasics. Both before and after treatment, which focused on naming of a series of pictures, naming-related brain activity was measured by magnetoencephalography (MEG). Due to its excellent temporal resolution and good spatial resolution, we were able to track treatment-induced changes in cortical activity. All three subjects showed improved naming of the trained items. In all subjects, a single source area, located in the left inferior parietal lobe, close to the lesioned area, displayed statistically significant training-induced changes. This effect was of long latency as it started 300 -600 msec after picture presentation. The change in activation was specific to training, as it could not be accounted for by variation of cortical dynamics associated with increased proportion of correct answers. Our interpretation is that the training effect reflects more effective phonological encoding and storage of the trained items through the engagement of a left hemispheric word-learning system. This is in line with recent functional imaging studies, which have linked left inferior parietal lobe activity to the phonological storage component of the verbal working memory, as well as with theoretical arguments stating that the primary role of the phonological loop is to acquire new words. Finally, the MEG results showed no evidence of increased right hemisphere participation following training, supporting the view that restoration of language-related networks in the damaged left hemisphere is crucial for anomia recovery. &

Dynamics of phonological–phonetic encoding in word production: Evidence from diverging ERPs between stroke patients and controls

“…starting ~300ms after picture presentation, were observed, on the other hand, in aphasic speakers with predominantly lexical-phonological Time-course of phonetic encoding 6 encoding impairments (Laganaro et al, 2009. Similar results were reported in a MEG study on recovery from anomia in patients with lexical-phonological impairments (Cornelissen et al, 2003). Here, MEG changes between pre-and post-treatment assessments were observed starting at 300ms after picture presentation.…”

“…between 100-250ms after stimulus onset) or lexical-phonological impairments (i.e. from 300ms after stimulus onset ;Cornelissen et al, 2003;Laganaro et al, 2008;2009;2011). In previous studies, the atypical ERPs observed in sub-groups of anomic patients converged with the dynamics of encoding processes estimated in healthy subjects (Indefrey & Levelt, 2004;Indefrey, 2011).…”

“…Indeed, patients classified as impaired at the lexical-phonological level in former studies or at the phonological-phonetic level in the present study all produced Time-course of phonetic encoding 22 phonemic paraphasias in picture naming tasks. However, formerly investigated patients also presented high rates of non-responses (up to 50% in Cornelissen et al, 2003;up to 79% in Laganaro et al, 2009), indicating underlying word-finding impairments (i.e. lexicalphonological impairments).…”

“…While in the study of Cornelissen et al (2003) a pre-post treatment comparison was used, Laganaro et al (2009) employed a delayed production task whose results are comparable to immediate production only during the first 350ms (Laganaro & Perret, 2011).…”

Comparing Electrophysiological Correlates of Word Production in Immediate and Delayed Naming Through the Analysis of Word Age of Acquisition Effects

“…Alternatively, ERP studies on word production have used silent or delayed production paradigms during picture naming (Cornelissen et al, 2003;Jescheniak, Hahne, & Schriefers, 2003;Laganaro, Morand, & Schnider, 2009;Vihla, Laine, & Salmelin, 2006). In these studies participants either prepared the word (producing it overtly after a delay falling beyond the analysed period), or they said the word in their mind, therefore also avoiding possible artefacts during motor preparation and execution.…”