Statistical learning (SL) is the ability to detect and learn regularities from input and is foundational to language acquisition. Despite the dominant role of SL as a theoretical construct for language development, there is a lack of direct evidence supporting the shared neural substrates underlying language processing and SL. It is also not clear whether the similarities, if any, are related to linguistic processing, or statistical regularities in general.
View Article and Find Full Text PDFImportant recent advances in the cognitive neuroscience of language have been made using functional localizers to demarcate language-selective regions in individual brains. Although single-subject localizers offer insights that are unavailable in classic group analyses, they require additional scan time that imposes costs on investigators and participants. In particular, the unique practical challenges of scanning children and other special populations has led to less adoption of localizers for neuroimaging research with these theoretically and clinically important groups.
View Article and Find Full Text PDFPurpose: Non-HIV cryptococcal meningoencephalitis (CM) in previously healthy individuals is often complicated by a post-infectious inflammatory response syndrome (c-PIIRS) characterized by neurologic deterioration after appropriate antifungal therapy with sterilization of CSF fungal cultures. c-PIIRS results from an excessive inflammatory response to fungal antigens released during fungal lysis, mediated by IFN-γ, IL-6, and activated T-helper cells, leading to immune-mediated host damage that responds to pulse-corticosteroid taper therapy (PCT). Typically, oral steroids may take up to a year to taper, and occasionally, patients will be refractory to steroid therapy or may demonstrate high-risk lesions such as those involving intracranial arteries.
View Article and Find Full Text PDFBackground: Apraxia of speech is a disorder of speech-motor planning in which articulation is effortful and error-prone despite normal strength of the articulators. Phonological alexia and agraphia are disorders of reading and writing disproportionately affecting unfamiliar words. These disorders are almost always accompanied by aphasia.
View Article and Find Full Text PDFClassical models have traditionally focused on the left posterior inferior frontal gyrus (Broca's area) as a key region for motor planning of speech production. However, converging evidence suggests that it is not critical for either speech motor planning or execution. Alternative cortical areas supporting high-level speech motor planning have yet to be defined.
View Article and Find Full Text PDFBackground: Cryptococcal meningoencephalitis (CM) is a major cause of mortality in immunosuppressed patients and previously healthy individuals. In the latter, a post-infectious inflammatory response syndrome (PIIRS) is associated with poor clinical response despite antifungal therapy and negative cerebrospinal fluid (CSF) cultures. Data on effective treatment are limited.
View Article and Find Full Text PDFSensorimotor adaptation-enduring changes to motor commands due to sensory feedback-allows speakers to match their articulations to intended speech acoustics. How the brain integrates auditory feedback to modify speech motor commands and what limits the degree of these modifications remain unknown. Here, we investigated the role of speech motor cortex in modifying stored speech motor plans.
View Article and Find Full Text PDFSensorimotor adaptation experiments are commonly used to examine motor learning behavior and to uncover information about the underlying control mechanisms of many motor behaviors, including speech production. In the speech and voice domains, aspects of the acoustic signal are shifted/perturbed over time via auditory feedback manipulations. In response, speakers alter their production in the opposite direction of the shift so that their perceived production is closer to what they intended.
View Article and Find Full Text PDFPhonological working memory is the capacity to briefly maintain and recall representations of sounds important for speech and language and is believed to be critical for language and reading acquisition. Whether phonological working memory is supported by fronto-parietal brain regions associated with short-term memory storage or perisylvian brain structures implicated in speech perception and production is unclear, perhaps due to variability in stimuli, task demands, and individuals. We used fMRI to assess neurophysiological responses while individuals performed two tasks with closely matched stimuli but divergent task demands-nonword repetition and nonword discrimination-at two levels of phonological working memory load.
View Article and Find Full Text PDFThe neural processes that underlie your ability to read and understand this sentence are unknown. Sentence comprehension occurs very rapidly, and can only be understood at a mechanistic level by discovering the precise sequence of underlying computational and neural events. However, we have no continuous and online neural measure of sentence processing with high spatial and temporal resolution.
View Article and Find Full Text PDFA set of brain regions in the frontal, temporal, and parietal lobes supports high-level linguistic processing. These regions can be reliably identified in individual subjects using fMRI, by contrasting neural responses to meaningful and structured language stimuli vs. stimuli matched for low-level properties but lacking meaning and/or structure.
View Article and Find Full Text PDFBoth smoking and nicotine can facilitate cognitive efficiency in humans, however the exact mechanism underlying this improvement in cognitive performance is unclear. Nicotine-related improvements in visual task performance may stem from facilitation of the identification and encoding of rare deviant stimuli at early sensory levels. Visual processes at these early levels are thought to be indexed by the visual mismatch negativity (vMMN), an event-related potential (ERP) measure of pre-conscious deviant detection.
View Article and Find Full Text PDFResearch into the effects of nicotine and smoking on cognition has largely confirmed the subjective reports of smoking in smokers on mental functions, showing smoking abstinence to disrupt and smoking/nicotine to restore cognitive functioning. Evidence of performance improvements in nonsmokers has provided partial support for the absolute effects of nicotine on cognitive processes, which are independent of withdrawal relief, but the mechanisms underlying its pro-cognitive properties still remain elusive. The attentional facilitation frequently reported with smoking/nicotine may be indirectly related to its diffuse arousal-enhancing actions, as evidenced by electroencephalographic (EEG) fast frequency power increments, or it may reflect nicotine's direct modulating effects on specific neural processes governing stimulus encoding, selection and rejection.
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