The role of the hippocampus in statistical learning and language recovery in persons with post stroke aphasia

Schevenels, Klara; Michiels, Laura; Lemmens, Robin; Smedt, Bert De; Zink, Inge; Vandermosten, Maaike

doi:10.1016/j.nicl.2022.103243

Cited by 12 publications

(9 citation statements)

References 148 publications

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“…High-frequency oscillations and coupled activity with the theta-band are reportedly reflecting networks of hippocampal inhibitory interneurons (Bartos et al, 2007; Herrmann & Demiralp, 2005) associated with memory, attentive and learning processes (Bartos et al, 2007; Belluscio et al, 2012; Colgin et al, 2009; Kay, 2003). Interestingly, these cognitive functions were recently shown to be intact in PWA (Schevenels et al, 2022), leading to the speculation that protective or compensatory mechanisms might be reflected in weakened low-gamma-band network. Our results may seem in contrast with previous studies reporting either stronger connectivity (Snyder et al, 2021) or alteration in alpha- and beta-band networks (P. Shah-Basak et al, 2022) in chronic aphasia.…”

Section: Discussionmentioning

confidence: 99%

“…PWA were recruited within the cohort of participants at the stroke unit of the University Hospital Leuven, Belgium (UZ Leuven), within a larger project comprising other research works (Kries et al, 2022). Screening was performed using a Dutch adaptation of the Language Screening Test (LAST) (Flamand-Roze et al, 2011;Schevenels et al, 2020Schevenels et al, , 2022, and only patients with LAST score equal or below the cut-off score (i.e., 14/15) and with left-hemispheric or bilateral lesion were recruited. For each included patient, the experimental session took place at least six months after the stroke onset (median: 19 months; range: 6-369 months).…”

Section: Participantsmentioning

confidence: 99%

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EEG reveals brain network alterations in chronic aphasia during natural speech listening

Mehraram

Kries

Clercq

et al. 2023

Preprint

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Aphasia is a common consequence of a stroke which affects language processing. In search of an objective biomarker for aphasia, we used EEG to investigate how functional network patterns in the cortex are affected in persons with post-stroke chronic aphasia (PWA) compared to healthy controls (HC) while they are listening to a story. EEG was recorded from 22 HC and 27 PWA while they listened to a 25-min-long story. Functional connectivity between scalp regions was measured with the weighted phase lag index. The Network-Based Statistics toolbox was used to detect altered network patterns and to investigate correlations with behavioural tests within the aphasia group. Differences in network geometry were assessed by means of graph theory and a targeted node-attack approach. Group-classification accuracy was obtained with a support vector machine classifier. PWA showed stronger inter-hemispheric connectivity compared to HC in the theta-band (4.5-7 Hz), whilst a weaker subnetwork emerged in the low-gamma band (30.5-49 Hz). Two subnetworks correlated with semantic fluency in PWA respectively in delta- (1-4 Hz) and low-gamma-bands. In the theta-band network, graph alterations in PWA emerged at both local and global level, whilst only local changes were found in the low-gamma-band network. As assessed with the targeted node-attack, PWA exhibit a more scale-free network compared to HC. Network metrics effectively discriminated PWA and HC (AUC = 83%). Overall, we showed for that EEG-network metrics are effective biomarkers to assess natural speech processing in chronic aphasia. We hypothesize that the detected alterations reflect compensatory mechanisms associated with recovery.

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Section: Discussionmentioning

confidence: 99%

Section: Participantsmentioning

confidence: 99%

EEG reveals brain network alterations in chronic aphasia during natural speech listening

Mehraram

Kries

Clercq

et al. 2023

Preprint

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“…The lesions were manually segmented using MRIcron (v. 02092019), guided by the information documented in their respective medical ﬁles (written by a neurologist/neuroradiologist). Brain scans were acquired in the acute stage post-stroke (between 3-7 days) for 26 IWA, and 13 IWA had lesion data in post-stroke stage ≥ 4 months when participating in other studies performed in our research lab (Schevenels et al, 2022; De Clercq et al, 2024a). After segmentation, all brain scans and lesion masks were normalized to the template for older individuals in MNI space with the Clinical Toolbox implemented in SPM (Rorden et al, 2012).…”

Section: Methodsmentioning

confidence: 99%

Neural substrates and behavioral relevance of speech envelope tracking: evidence from post-stroke aphasia

De Clercq,

Kries,

Vanthornhout

et al. 2024

Preprint

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Neural tracking of the low-frequency temporal envelope of speech has emerged as a prominent tool to investigate the neural mechanisms of natural speech processing in the brain. However, there is ongoing debate regarding the functional role of neural envelope tracking. In this context, our study aims to offer a novel perspective by investigating the critical brain areas and behavioral skills required for neural envelope tracking in aphasia, a language disorder characterized by impaired neural envelope tracking. We analyzed an EEG dataset of 39 individuals with post-stroke aphasia suffering a left-hemispheric stroke who listened to natural speech. Our analysis involved lesion mapping, where left lesioned brain voxels served as binary features to predict neural envelope tracking measures. We also examined the behavioral correlates of receptive language, naming, and auditory processing (via rise time discrimination task) skills. The lesion mapping analysis revealed that lesions in language areas, such as the middle temporal gyrus, supramarginal gyrus and angular gyrus, were associated with poorer neural envelope tracking. Additionally, neural tracking was related to auditory processing skills and language (receptive and naming) skills. However, the effects on language skills were less robust, possibly due to ceiling effects in the language scores. Our findings highlight the importance of central brain areas implicated in language understanding, extending beyond the primary auditory cortex, and emphasize the role of intact auditory processing and language abilities in effectively processing the temporal envelope of speech. Collectively, these findings underscore the significance of neural envelope tracking beyond mere audibility and acoustic processes.

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“…Patients further completed a custom-made demographic questionnaire. Other measures collected, such as statistical learning measures, are outside the scope of this study and are reported elsewhere ( Schevenels et al, 2022 ). In the chronic phase, the ScreeLing ( Visch-Brink et al, 2010 ) was again readministered.…”

Section: Methodsmentioning

confidence: 99%

Early white matter connectivity and plasticity in post stroke aphasia recovery

Schevenels

Gerrits

Lemmens

et al. 2022

NeuroImage: Clinical

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The role of the hippocampus in statistical learning and language recovery in persons with post stroke aphasia

Cited by 12 publications

References 148 publications

EEG reveals brain network alterations in chronic aphasia during natural speech listening

EEG reveals brain network alterations in chronic aphasia during natural speech listening

Neural substrates and behavioral relevance of speech envelope tracking: evidence from post-stroke aphasia

Early white matter connectivity and plasticity in post stroke aphasia recovery

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