Nervous System Commons^™

Partial Least Squares Multimodal Analysis Of Brain Network Correlates Of Language Deficits In Aphasia, Sigfus Kristinsson, Dirk B. Den Ouden, Chris Rorden, Roger Newman-Norlund, Lisa Johnson, Janina Wilmskoetter, Ezequiel Gleichgerrcht, Argye E. Hillis, Gregory Hickok, Julius Fridriksson, Leonardo Bonilha

Communication Sciences and Disorders Faculty Articles and Research

Lesion-symptom mapping techniques are essential to determine brain regions critical for language functions. However, high collinearity in neuroimaging and behavioural data remains a challenge for distinguishing neural substrates supporting multiple language domains (shared variance) and those subserving specific language functions (unique variance). Here, we employed a novel approach to multimodal lesion-symptom mapping using multivariate partial least squares regression to delineate the latent structure of lesion-behavioural mapping in aphasia and decompose the shared and unique neural determinants of language impairments. A total of 86 participants with chronic (>12-month post-stroke) aphasia after left hemisphere strokes were examined. Language impairment was assessed …

Benchmarking Machine Learning Models In Lesion-Symptom Mapping For Predicting Language Outcomes In Stroke Survivors, Deepa Tilwani, Christian O'Reilly, Nicholas Riccardi, Valerie L. Shalin, Dirk B. Den Ouden, Julius Fridriksson, Svetlana V. Shinkareva, Amit P. Sheth, Rutvik H. Desai

Communication Sciences and Disorders Faculty Articles and Research

Several decades of research have investigated the neural connections between stroke-induced brain damage and language difficulties. Typically, lesion-symptom mapping (LSM) studies that address this connection have relied on mass univariate statistics, which do not account for multidimensional relationships between variables. Machine learning (ML) techniques, which can capture these intricate connections, offer a promising complement to LSM methods. To test this promise, we benchmarked ML models on structural and functional MRI to predict aphasia severity (N = 238) and naming impairment (N = 191) for a cohort of chronic-stage stroke survivors. We used nested cross-validation to examine performance along …

Verbal Working Memory And Syntactic Comprehension Segregate Into The Dorsal And Ventral Streams, Respectively, William Matchin, Zeinab K. Mollasaraei, Leonardo Bonilha, Christopher Rorden, Gregory Hickok, Dirk B. Den Ouden, Julius Fridriksson

Communication Sciences and Disorders Faculty Articles and Research

Syntactic processing and verbal working memory are both essential components to sentence comprehension. Nonetheless, the separability of these systems in the brain remains unclear. To address this issue, we performed causal-inference analyses based on lesion and connectome network mapping using MRI and behavioural testing in two groups of individuals with chronic post-stroke aphasia. We employed a rhyme judgement task with heavy working memory load without articulatory confounds, controlling for the overall ability to match auditory words to pictures and to perform a metalinguistic rhyme judgement, isolating the effect of working memory load (103 individuals). We assessed non-canonical sentence comprehension, isolating …

Dissociating Reading And Auditory Comprehension In Persons With Aphasia, Rachael M. Harrington, Sigfus Kristinsson, Janina Wilmskoetter, Natalie Busby, Dirk B. Den Ouden, Chris Rorden, Julius Fridriksson, Leonardo Bonilha

Communication Sciences and Disorders Faculty Articles and Research

Language comprehension is often affected in individuals with post-stroke aphasia. However, deficits in auditory comprehension are not fully correlated with deficits in reading comprehension and the mechanisms underlying this dissociation remain unclear. This distinction is important for understanding language mechanisms, predicting long-term impairments and future development of treatment interventions. Using comprehensive auditory and reading measures from a large cohort of individuals with aphasia, we evaluated the relationship between aphasia type and reading comprehension impairments, the relationship between auditory versus reading comprehension deficits and the crucial neuroanatomy supporting the dissociation between post-stroke reading and auditory deficits. Scores from the Western Aphasia …

Brain Age Predicts Long-Term Recovery In Post-Stroke Aphasia, Sigfus Kristinsson, Natalie Busby, Christopher Rorden, Roger Newman-Norlund, Dirk B. Den Ouden, Sigridur Magnusdottir, Haukur Hjaltason, Helga Thors, Argye E. Hillis, Olafur Kjartansson, Leonardo Bonilha, Julius Fridriksson

Communication Sciences and Disorders Faculty Articles and Research

The association between age and language recovery in stroke remains unclear. Here, we used neuroimaging data to estimate brain age, a measure of structural integrity, and examined the extent to which brain age at stroke onset is associated with (i) cross-sectional language performance, and (ii) longitudinal recovery of language function, beyond chronological age alone. A total of 49 participants (age: 65.2 ± 12.2 years, 25 female) underwent routine clinical neuroimaging (T1) and a bedside evaluation of language performance (Bedside Evaluation Screening Test-2) at onset of left hemisphere stroke. Brain age was estimated from enantiomorphically reconstructed brain scans using a machine …

Functional Differentiation In The Language Network Revealed By Lesion-Dymptom Mapping, William Matchin, Alexandra Basilakos, Dirk B. Den Ouden, Brielle C. Stark, Gregory Hickok, Julius Fridriksson

Communication Sciences and Disorders Faculty Articles and Research

Theories of language organization in the brain commonly posit that different regions underlie distinct linguistic mechanisms. However, such theories have been criticized on the grounds that many neuroimaging studies of language processing find similar effects across regions. Moreover, condition by region interaction effects, which provide the strongest evidence of functional differentiation between regions, have rarely been offered in support of these theories. Here we address this by using lesion-symptom mapping in three large, partially-overlapping groups of aphasia patients with left hemisphere brain damage due to stroke (N = 121, N = 92, N = 218). We identified multiple measure by …

Agrammatism And Paragrammatism: A Cortical Double Dissociation Revealed By Lesion-Symptom Mapping, William Matchin, Alexandra Basilakos, Brielle C. Stark, Dirk B. Den Ouden, Fridolin Gross, Gregory Hickok

Communication Sciences and Disorders Faculty Articles and Research

The fundamental distinction of grammatical deficits in aphasia, agrammatism and paragrammatism, was made over a century ago. However, the extent to which the agrammatism/paragrammatism distinction exists independently of differences in speech fluency has not clearly been investigated. Despite much research on agrammatism, the lesion correlates of paragrammatism are essentially unknown. Lesion-symptom mapping was used to investigate the degree to which the lesion correlates of agrammatism and paragrammatism overlap or dissociate. Four expert raters assessed videos of 53 right-handed patients with aphasia following chronic left-hemisphere stroke retelling the Cinderella story. Consensus discussion determined each subject’s classification with respect to grammatical deficits …

Treatment Of Auditory Processing In Noise In Individuals With Mild Aphasia: Pilot Study, Anastasia M. Raymer, Hilary M. Sandberg, Kathryn S. Schwartz, Ginger S. Watson, Stacie I. Ringleb

Communication Disorders & Special Education Faculty Publications

Purpose: Listening in noise challenges listeners with auditory comprehension impairments in aphasia. We examined the effects of Trivia Game, a computerized program with questions spoken in increasing levels of background noise with success in the game.

Methods: We piloted Trivia Game in four individuals with chronic aphasia and mild auditory comprehension impairments. Participants played Trivia Game for 12 twenty-minute sessions. In addition to the Western Aphasia Battery (WAB), we measured outcomes on Quick Speech in Noise (QSIN), a sentence repetition test, administered in auditory (AUD) and auditory+visual (AV) conditions as signal-to-noise ratio varied from 25 to 0 dB.

Results: All …

Revealing The Dual Streams Of Speech Processing, Julius Fridriksson, Grigori Yourganov, Leonardo Bonilha, Alexandra Basilakos, Dirk B. Den Ouden, Chris Rorden

Communication Sciences and Disorders Faculty Articles and Research

Several dual route models of human speech processing have been proposed suggesting a large-scale anatomical division between cortical regions that support motor–phonological aspects vs. lexical–semantic aspects of speech processing. However, to date, there is no complete agreement on what areas subserve each route or the nature of interactions across these routes that enables human speech processing. Relying on an extensive behavioral and neuroimaging assessment of a large sample of stroke survivors, we used a data-driven approach using principal components analysis of lesion-symptom mapping to identify brain regions crucial for performance on clusters of behavioral tasks without a priori separation into …