We investigated which parts of the cerebellum are involved in formulating and articulating sentences using (i) a sentence production task that involved describing simple events in pictures; (ii) an auditory sentence repetition task involving the same sentence articulation but not sentence formulation; and (iii) an auditory sentence-to-picture matching task that involved the same pictorial events and no overt articulation. Activation for each of these tasks was compared to the equivalent word processing tasks: noun production, verb production, auditory noun repetition, and auditory noun-to-picture matching. We associate activation in bilateral cerebellum lobule VIIb with sequencing words into sentences because it increased for sentence production compared to all other conditions and was also activated by word production compared to word matching.
View Article and Find Full Text PDFBoth 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.
View Article and Find Full Text PDFFunctional imaging studies of neurotypical adults report activation in the left putamen during speech production. The current study asked how stroke survivors with left putamen damage are able to produce correct spoken responses during a range of speech production tasks. Using functional magnetic resonance imaging, activation during correct speech production responses was assessed in 5 stroke patients with circumscribed left dorsal striatal lesions, 66 stroke patient controls who did not have focal left dorsal striatal lesions, and 54 neurotypical adults.
View Article and Find Full Text PDFUsing 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.
View Article and Find Full Text PDFPre- and intra-operative language mapping in neurosurgery patients frequently involves an object naming task. The choice of the optimal object naming paradigm remains challenging due to lack of normative data and standardization in mapping practices. The aim of this study was to identify object naming paradigms that robustly and consistently activate classical language regions and could therefore be used to improve the sensitivity of language mapping in brain tumor and epilepsy patients.
View Article and Find Full Text PDFPrior studies have shown that the left posterior superior temporal sulcus (pSTS) and left temporo-parietal junction (TPJ) both contribute to phonological short-term memory, speech perception and speech production. Here, by conducting a within-subjects multi-factorial fMRI study, we dissociate the response profiles of these regions and a third region - the anterior ascending terminal branch of the left superior temporal sulcus (atSTS), which lies dorsal to pSTS and ventral to TPJ. First, we show that each region was more activated by (i) 1-back matching on visually presented verbal stimuli (words or pseudowords) compared to 1-back matching on visually presented non-verbal stimuli (pictures of objects or non-objects), and (ii) overt speech production than 1-back matching, across 8 types of stimuli (visually presented words, pseudowords, objects and non-objects and aurally presented words, pseudowords, object sounds and meaningless hums).
View Article and Find Full Text PDFControversy surrounds the interpretation of higher activation for pseudoword compared to word reading in the left precentral gyrus and pars opercularis. Specifically, does activation in these regions reflect: (1) the demands on sublexical assembly of articulatory codes, or (2) retrieval effort because the combinations of articulatory codes are unfamiliar? Using fMRI, in 84 neurologically intact participants, we addressed this issue by comparing reading and repetition of words (W) and pseudowords (P) to naming objects (O) from pictures or sounds. As objects do not provide sublexical articulatory cues, we hypothesis that retrieval effort will be greater for object naming than word repetition/reading (which benefits from both lexical and sublexical cues); while the demands on sublexical assembly will be higher for pseudoword production than object naming.
View Article and Find Full Text PDFBroca's area in the posterior half of the left inferior frontal gyrus has traditionally been considered an important node in the speech production network. Nevertheless, recovery of speech production has been reported, to different degrees, within a few months of damage to Broca's area. Importantly, contemporary evidence suggests that, within Broca's area, its posterior part (i.
View Article and Find Full Text PDFSpecific regions of the cerebellum are activated when neurologically intact adults speak, and cerebellar damage can impair speech production early after stroke, but how the brain supports accurate speech production years after cerebellar damage remains unknown. We investigated this in patients with cerebellar lesions affecting regions that are normally recruited during speech production. Functional MRI activation in these patients, measured during various single word production tasks, was compared to that of neurologically intact controls, and patient controls with lesions that spared the cerebellar speech production regions.
View Article and Find Full Text PDFAn important aim of research on bilingualism is to understand how the brain adapts to the demands of using more than one language.In this paper, we argue that pursuing such an aim entails valuing our research as a discovery process that acts on variety.Prescriptions about sample size and methodology, rightly aimed at establishing a sound basis for generalization, should be understood as being in the service of science as a discovery process.
View Article and Find Full Text PDFSynthetic protocells are rudimentary origin-of-life versions of natural cell counterparts. Protocells are widely engineered to advance efforts and useful accepted outcomes in synthetic biology, soft matter chemistry and bioinspired materials chemistry. Protocells in collective symbiosis generate synthetic proto-tissues that display unprecedented autonomy and yield advanced materials with desirable life-like features for smart multi-drug delivery, micro bioreactors, renewable fuel production, environmental clean-up, and medicine.
View Article and Find Full Text PDFEstablishing whether speech and language therapy after stroke has beneficial effects on speaking ability is challenging because of the need to control for multiple non-therapy factors known to influence recovery. We investigated how speaking ability at three time points post-stroke differed in patients who received varying amounts of clinical therapy in the first month post-stroke. In contrast to prior studies, we factored out variance from: initial severity of speaking impairment, amount of later therapy, and left and right hemisphere lesion size and site.
View Article and Find Full Text PDFDiversity, equity, and inclusion (DEI) have become increasingly recognized as essential to the practice of high-quality patient care delivery and the support of members of the clinical environment. A solid understanding of DEI contributes to a better grasp of what drives health care disparities and yields improved clinical outcomes for minority populations. This column discusses how individuals can practically promote DEI by describing the design and implementation of DEI in an academic psychiatry department.
View Article and Find Full Text PDFFunctional imaging studies of neurologically intact adults have demonstrated that the right posterior cerebellum is activated during verb generation, semantic processing, sentence processing, and verbal fluency. Studies of patients with cerebellar damage converge to show that the cerebellum supports sentence processing and verbal fluency. However, to date there are no patient studies that investigated the specific importance of the right posterior cerebellum in language processing, because: (i) case studies presented patients with lesions affecting the anterior cerebellum (with or without damage to the posterior cerebellum), and (ii) group studies combined patients with lesions to different cerebellar regions, without specifically reporting the effects of right posterior cerebellar damage.
View Article and Find Full Text PDFPrior studies have reported inconsistency in the lesion sites associated with verbal short-term memory impairments. Here we asked: How many different lesion sites can account for selective impairments in verbal short-term memory that persist over time, and how consistently do these lesion sites impair verbal short-term memory? We assessed verbal short-term memory impairments using a forward digit span task from the Comprehensive Aphasia Test. First, we identified the incidence of digit span impairments in a sample of 816 stroke survivors (541 males/275 females; age at stroke onset 56 ± 13 years; time post-stroke 4.
View Article and Find Full Text PDFBroca's area in the posterior half of the left inferior frontal gyrus has long been thought to be critical for speech production. The current view is that long-term speech production outcome in patients with Broca's area damage is best explained by the combination of damage to Broca's area and neighbouring regions including the underlying white matter, which was also damaged in Paul Broca's two historic cases. Here, we dissociate the effect of damage to Broca's area from the effect of damage to surrounding areas by studying long-term speech production outcome in 134 stroke survivors with relatively circumscribed left frontal lobe lesions that spared posterior speech production areas in lateral inferior parietal and superior temporal association cortices.
View Article and Find Full Text PDFUnderstanding the aetiology of the diverse recovery patterns in bilingual aphasia is a theoretical challenge with implications for treatment. Loss of control over intact language networks provides a parsimonious starting point that can be tested using in-silico lesions. We simulated a complex recovery pattern (alternate antagonism and paradoxical translation) to test the hypothesis-from an established hierarchical control model-that loss of control was mediated by constraints on neuromodulatory resources.
View Article and Find Full Text PDFCurrent control of pathogenic bacteria at all biomaterial interfaces is poorly attuned to a broad range of disease-causing pathogens. Leading antimicrobial surface functionalization strategies with antimicrobial peptides (AMPs), defensins, have not shown their promised efficacy. One of the main problems is the lack of stability and swift clearance from the surface.
View Article and Find Full Text PDFMost marine materials, by nature, contain crystals of inorganic matter with specific structures that allow the loading, release, and delivery of biomolecules that can be utilized in clinical applications. These structures can be biomimetically synthesized. Aggregates of inorganic particles generated by biomimetic microsponges may provide surfaces and structures for cell attachment, organization, and promotion of matrix synthesis.
View Article and Find Full Text PDFThe efficient genesis of pluripotent cells or therapeutic cells for regenerative medicine involves several external manipulations and conditioning protocols, which drives down clinical applicability. Automated programming of the genesis by microscale physical forces and chronological biochemistry can increase clinical success. The design and fabrication of nested polysaccharide droplets (millimeter-sized) with cell sustaining properties of natural tissues and intrinsic properties for time and space evolution of cell transformation signals between somatic cells, pluripotent cells and differentiated therapeutic cells in a swift and efficient manner without the need for laborious external manipulation are reported.
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