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Author: search.filters.author.Justyna O. EkertSubject: search.filters.subject.speech

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    Degeneracy in the neurological model of auditory speech repetition
    (2023)
    Noor Sajid
    ;
    GAJARDO VIDAL, ANDREA ELIZABETH  
    ;
    Justyna O. Ekert
    ;
    Diego L. Lorca-Puls
    ;
    Thomas M. H. Hope
    <jats:title>Abstract</jats:title><jats:p>Both classic and contemporary models of auditory word repetition involve at least four left hemisphere regions: primary auditory cortex for processing sounds; pSTS (within Wernicke’s area) for processing auditory images of speech; pOp (within Broca’s area) for processing motor images of speech; and primary motor cortex for overt speech articulation. Previous functional-MRI (fMRI) studies confirm that auditory repetition activates these regions, in addition to many others. Crucially, however, contemporary models do not specify how regions interact and drive each other during auditory repetition. Here, we used dynamic causal modelling, to test the functional interplay among the four core brain regions during single auditory word and pseudoword repetition. Our analysis is grounded in the principle of degeneracy—i.e., many-to-one structure-function relationships—where multiple neural pathways can execute the same function. Contrary to expectation, we found that, for both word and pseudoword repetition, (i) the effective connectivity between pSTS and pOp was predominantly bidirectional and inhibitory; (ii) activity in the motor cortex could be driven by either pSTS or pOp; and (iii) the latter varied both within and between individuals. These results suggest that different neural pathways can support auditory speech repetition. This degeneracy may explain resilience to functional loss after brain damage.</jats:p>
    Scopus© Citations 3  2
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    A functional dissociation of the left frontal regions that contribute to single word production tasks
    (2021)
    Justyna O. Ekert
    ;
    Diego L. Lorca-Puls
    ;
    GAJARDO VIDAL, ANDREA ELIZABETH  
    ;
    Jennifer T. Crinion
    ;
    Thomas M.H. Hope
    Scopus© Citations 10  2
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    Scopus© Citations 11  1
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    The Effect of Right Temporal Lobe Gliomas on Left and Right Hemisphere Neural Processing During Speech Perception and Production Tasks
    (2022)
    Adam Kenji Yamamoto
    ;
    Ana Sanjuán
    ;
    Rebecca Pope
    ;
    Oiwi Parker Jones
    ;
    Thomas M. H. Hope
    Using fMRI, we investigated how right temporal lobe gliomas affecting the posterior superior temporal sulcus alter neural processing observed during speech perception and production tasks. Behavioural language testing showed that three pre-operative neurosurgical patients with grade 2, grade 3 or grade 4 tumours had the same pattern of mild language impairment in the domains of object naming and written word comprehension. When matching heard words for semantic relatedness (a speech perception task), these patients showed under-activation in the tumour infiltrated right superior temporal lobe compared to 61 neurotypical participants and 16 patients with tumours that preserved the right postero-superior temporal lobe, with enhanced activation within the (tumour-free) contralateral left superior temporal lobe. In contrast, when correctly naming objects (a speech production task), the patients with right postero-superior temporal lobe tumours showed higher activation than both control groups in the same right postero-superior temporal lobe region that was under-activated during auditory semantic matching. The task dependent pattern of under-activation during the auditory speech task and over-activation during object naming was also observed in eight stroke patients with right hemisphere infarcts that affected the right postero-superior temporal lobe compared to eight stroke patients with right hemisphere infarcts that spared it. These task-specific and site-specific cross-pathology effects highlight the importance of the right temporal lobe for language processing and motivate further study of how right temporal lobe tumours affect language performance and neural reorganisation. These findings may have important implications for surgical management of these patients, as knowledge of the regions showing functional reorganisation may help to avoid their inadvertent damage during neurosurgery.
      10Scopus© Citations 8