Differences in Speech Perception and Production Networks Between Persons who stutter and Controls

Previous research has demonstrated atypical lateralization and brain asymmetry in persons who stutter (PWS). It has also been demonstrated that PWS show atypical activation patterns when processing language stimuli. We wanted to investigate differences between PWS and controls in speech perception and production processing tasks. Dichotic listening (DL) and soundmorph fMRI paradigms were applied to obtain functional measures. In addition we investigated structural differences by using diffusion tensor imaging (DTI) and analysing our data with voxel-based morphometry (VBM). The results indicate that stuttering is related to abnormal activation patterns in both speech perception and production. There were bilateral differences in activation between PWS and controls in both the soundmorph paradigm and the DL production task. However, in the DL paradigm, the results were only significant with an uncorrected p-value. We also found lower fractional anisotropy (FA) (at an uncorrected level) in PWS in left inferior frontal gyrus (IFG), indicating dysfunctional connectivity, but no differences in grey matter. The results lend support towards functional abnormalities in speech lateralization, and to a differential involvement of the dorsal stream of speech processing in PWS. The results also lend support to the notion of a strong involvement of STS in speech perception in both PWS and controls. However, these this study is part of an ongoing project, and the findings may change as more data is collected.Forskning har vist atypisk lateralisering og strukturell hjerneasymmetri hos personer som stammer (PSS). I tillegg har man funnet atypiske hjerneaktiveringsmønstre hos stammere under ulike oppgaver som involverer språkprosessering. Formålet med vår studie var å undersøke forskjeller mellom en gruppe med PSS og en kontrollgruppe under utførelse av talepersepsjons- og taleproduksjonsoppgaver. Funksjonelle avvik ble undersøkt med to fMRI-paradigmer, dikotisk lytting (DL) og soundmorph. Strukturelle avvik ble undersøkt med "diffusion tensor imaging" (DTI) og voxelbasert morfometri (VBM). Resultatene indikerer at stamming er knyttet til avvikende hjerneaktiveringsmønstre, både i talepersepsjon og taleproduksjon. Vi fant bilaterale forskjeller i aktivering i PSS og kontrollgruppen i både soundmorph- og DL-paradigmene, selv om funnene i DL bare er signifikante med ukorrigert p-verdi. Strukturundersøkelsene viste lavere grad av fraksjonell anisotropi (FA) (med en ukorrigert p-verdi) i venstre inferior frontale gyrus (IFG) hos PSS - en indikasjon på dysfunksjonell konnektivitet, men ingen forskjeller i grå materie. Resultatene gir støtte til hypoteser om avvikende aktivering i talelateralisering, og ulik involvering av den dorsale taleprosesseringsstrømmen hos PSS. Funnene støtter også oppfatningen om sterk involvering av superior temporal sulcus (STS) i talepersepsjon hos både PSS og kontrollgruppen. Det understrekes imidlertid at våre funn er del av et større pågående prosjekt, og kan bli endret ettersom mer data innhentes.PSYK300PRPSY

How visual attention span and phonological skills contribute to N170 print tuning: An EEG study in French dyslexic students

Developmental dyslexia is a disorder characterized by a sustainable learning deficit in reading. Based on ERP-driven approaches focusing on the visual word form area, electrophysiological studies have pointed a lack of visual expertise for written word recognition in dyslexic readers by contrasting the left-lateralized N170 amplitudes elicited by alphabetic versus non-alphabetic stimuli. Here, we investigated in 22 dyslexic participants and 22 age-matched control subjects how two behavioural abilities potentially affected in dyslexic readers (phonological and visual attention skills) contributed to the N170 expertise during a word detection task. Consistent with literature, dyslexic participants exhibited poorer performance in these both abilities as compared to healthy subjects. At the brain level, we observed (1) an unexpected preservation of the N170 expertise in the dyslexic group suggesting a possible compensatory mechanism and (2) a modulation of this expertise only by phonological skills, providing evidence for the phonological mapping deficit hypothesis

Semantic radical consistency and character transparency effects in Chinese: an ERP study

BACKGROUND: This event-related potential (ERP) study aims to investigate the representation and temporal dynamics of Chinese orthography-to-semantics mappings by simultaneously manipulating character transparency and semantic radical consistency. Character components, referred to as radicals, make up the building blocks used dur...postprin

Structural and effective connectivity of lexical-semantic and naming networks in patients with chronic aphasia

Given the difficulty in predicting outcomes in persons with stroke-induced aphasia (PWA), neuroimaging-based biomarkers of recovery could provide invaluable predictive power to stroke models. However, the neural patterns that constitute beneficial neural organization of language in PWA remain debated. Thus, in this work, we propose a novel network theory of aphasia recovery and test our overarching hypothesis, i.e., that task-specific language processing in PWA requires the dynamic engagement of intact tissue within a bilateral network of anatomically-segregated but functionally and structurally connected language-specific and domain-general brain regions. We first present two studies in which we examined left frontotemporal connectivity during different language tasks (i.e., picture naming and semantic feature verification). Results suggest that PWA heavily rely on left middle frontal gyrus (LMFG)-driven connectivity for tasks requiring lexical-semantic processing and semantic control whereas controls prefer models with input to either LMFG or left inferior frontal gyrus (LIFG). Both studies also revealed several significant associations between spared tissue, connectivity and language skills in PWA. In the third study, we examined bilateral frontotemporoparietal connectivity and tested a lesion- and connectivity-based hierarchical model of chronic aphasia recovery. Between-group comparisons showed controls exhibited stronger left intra-hemispheric task-modulated connectivity than did PWA. Connectivity and language deficit patterns most closely matched predictions for patients with primarily anterior damage whereas connectivity results for patients with other lesion types were best explained by the nature of the semantic task. In the last study, we investigated the utility of lesion classification based on gray matter (GM) only versus combined GM plus white matter (WM) metrics. Results suggest GM only classification was sufficient for characterizing aphasia and anomia severity but the GM+WM classification better predicted naming treatment outcomes. We also found that fractional anisotropy of left WM association tracts predicted baseline naming and treatment outcomes independent of total lesion volume. Finally, results of a preliminary multimodal prediction analysis suggest that combined structural and functional metrics reflecting the integrity of regions and connections comprise optimal predictive models of behavior in PWA. To conclude this dissertation, we discuss how multimodal network models of aphasia recovery can guide future investigations.2020-10-23T00:00:00