Project description:In this study, we investigated how the brain responds to task difficulty in linguistic and non-linguistic contexts. This is important for the interpretation of functional imaging studies of neuroplasticity in post-stroke aphasia, because of the inherent difficulty of matching or controlling task difficulty in studies with neurological populations. Twenty neurologically normal individuals were scanned with fMRI as they performed a linguistic task and a non-linguistic task, each of which had two levels of difficulty. Critically, the tasks were matched across domains (linguistic, non-linguistic) for accuracy and reaction time, such that the differences between the easy and difficult conditions were equivalent across domains. We found that non-linguistic demand modulated the same set of multiple demand (MD) regions that have been identified in many prior studies. In contrast, linguistic demand modulated MD regions to a much lesser extent, especially nodes belonging to the dorsal attention network. Linguistic demand modulated a subset of language regions, with the left inferior frontal gyrus most strongly modulated. The right hemisphere region homotopic to Broca's area was also modulated by linguistic but not non-linguistic demand. When linguistic demand was mapped relative to non-linguistic demand, we also observed domain by difficulty interactions in temporal language regions as well as a widespread bilateral semantic network. In sum, linguistic and non-linguistic demand have strikingly different neural correlates. These findings can be used to better interpret studies of patients recovering from aphasia. Some reported activations in these studies may reflect task performance differences, while others can be more confidently attributed to neuroplasticity.
Project description:Imaging studies of language processing in clinical populations can be complicated to interpret for several reasons, one being the difficulty of matching the effortfulness of processing across individuals or tasks. To better understand how effortful linguistic processing is reflected in functional activity, we investigated the neural correlates of task difficulty in linguistic and non-linguistic contexts in the auditory modality and then compared our findings to a recent analogous experiment in the visual modality in a different cohort. Nineteen neurologically normal individuals were scanned with fMRI as they performed a linguistic task (semantic matching) and a non-linguistic task (melodic matching), each with two levels of difficulty. We found that left hemisphere frontal and temporal language regions, as well as the right inferior frontal gyrus, were modulated by linguistic demand and not by non-linguistic demand. This was broadly similar to what was previously observed in the visual modality. In contrast, the multiple demand (MD) network, a set of brain regions thought to support cognitive flexibility in many contexts, was modulated neither by linguistic demand nor by non-linguistic demand in the auditory modality. This finding was in striking contradistinction to what was previously observed in the visual modality, where the MD network was robustly modulated by both linguistic and non-linguistic demand. Our findings suggest that while the language network is modulated by linguistic demand irrespective of modality, modulation of the MD network by linguistic demand is not inherent to linguistic processing, but rather depends on specific task factors.
Project description:Neurolinguistic accounts of sentence comprehension identify a network of relevant brain regions, but do not detail the information flowing through them. We investigate syntactic information. Does brain activity implicate a computation over hierarchical grammars or does it simply reflect linear order, as in a Markov chain? To address this question, we quantify the cognitive states implied by alternative parsing models. We compare processing-complexity predictions from these states against fMRI timecourses from regions that have been implicated in sentence comprehension. We find that hierarchical grammars independently predict timecourses from left anterior and posterior temporal lobe. Markov models are predictive in these regions and across a broader network that includes the inferior frontal gyrus. These results suggest that while linear effects are wide-spread across the language network, certain areas in the left temporal lobe deal with abstract, hierarchical syntactic representations.
Project description:Gastrointestinal infection morbidity remains high amongst preschool children in developed countries. We investigated the societal burden (incidence, healthcare utilization, and productivity loss) and correlates of acute gastroenteritis (AGE) in families with preschoolers. Monthly for 25 months, 2000 families reported AGE symptoms and related care, productivity loss, and risk exposures for one preschooler and one parent. Amongst 8768 child-parent pairs enrolled, 7.3% parents and 17.4% children experienced AGE (0.95 episodes/parent-year and 2.25 episodes/child-year). Healthcare utilization was 18.3% (children) and 8.6% (parents), with 1.6% children hospitalized. Work absenteeism was 55.6% (median 1.5 days) and day-care absenteeism was 26.2% (median 1 day). Besides chronic enteropathies, antacid use, non-breastfeeding, and toddling age, risk factors for childhood AGE were having developmental disabilities, parental occupation in healthcare, multiple siblings, single-parent families, and ≤ 12-month day-care attendance. Risk factors for parental AGE were female gender, having multiple or developmentally-disabled day-care-attending children, antimicrobial use, and poor food-handling practices. Parents of AGE-affected children had a concurrent 4-fold increased AGE risk. We concluded that AGE-causing agents spread widely in families with preschool children, causing high healthcare-seeking behaviours and productivity losses. Modifiable risk factors provide targets for AGE-reducing initiatives. Children may acquire some immunity to AGE after one year of day-care attendance.
Project description:To evaluate which features of spoken language aid infant word learning, a corpus of infant-directed speech (M. R. Brent & J. M. Siskind, 2001) was characterized on several linguistic dimensions and statistically related to the infants' vocabulary outcomes word by word. Comprehension (at 12 and 15 months) and production (15 months) were predicted by frequency, frequency of occurrence in one-word utterances, concreteness, utterance length, and typical duration. These features have been proposed to influence learning before, but here their relative contributions were measured. Mothers' data predicted learning in their own children better than in other children; thus, vocabulary is measurably aligned within families. These analyses provide a quantitative basis for claims concerning the relevance of several properties of maternal English speech in facilitating early word learning.
Project description:Proverbs are usually regarded as structurally fixed expressions. However, in daily communication, language users often change them to suit their communicative purposes in many ways, resulting in proverb variations. Using the data from the Corpus of Contemporary American English (COCA corpus), this study attempts to present varieties of the English proverb "There are two sides to every coin" and explain the variations from the perspective of linguistic creativity. This study also explores the variations of this proverb in EFL learners' use via the data from Chinese EFL learners' corpus TECCL. The study shows that, first proverb use can roughly be divided into two types: canonical and non-canonical uses, each having three ways of alteration, i.e., addition of modifiers, substitution of content words, and reduction. Second, Chinese EFL learners tend to use the proverb in a mechanical way with little variation, which shows their inflexible use of proverbs. Finally, proverb variation by nature is the creative manipulation of language use to fit the context, which is a form of linguistic creativity that reflects the cognitive creativity of human beings.
Project description:ObjectivesThe notion that patterns of linguistic and biological variation may cast light on each other and on population histories dates back to Darwin's times; yet, turning this intuition into a proper research program has met with serious methodological difficulties, especially affecting language comparisons. This article takes advantage of two new tools of comparative linguistics: a refined list of Indo-European cognate words, and a novel method of language comparison estimating linguistic diversity from a universal inventory of grammatical polymorphisms, and hence enabling comparison even across different families. We corroborated the method and used it to compare patterns of linguistic and genomic variation in Europe.Materials and methodsTwo sets of linguistic distances, lexical and syntactic, were inferred from these data and compared with measures of geographic and genomic distance through a series of matrix correlation tests. Linguistic and genomic trees were also estimated and compared. A method (Treemix) was used to infer migration episodes after the main population splits.ResultsWe observed significant correlations between genomic and linguistic diversity, the latter inferred from data on both Indo-European and non-Indo-European languages. Contrary to previous observations, on the European scale, language proved a better predictor of genomic differences than geography. Inferred episodes of genetic admixture following the main population splits found convincing correlates also in the linguistic realm.DiscussionThese results pave the ground for previously unfeasible cross-disciplinary analyses at the worldwide scale, encompassing populations of distant language families.
Project description:Counterarguing is a key obstacle to successful persuasion. However, the difficulty of directly measuring counterarguing during message exposure limits knowledge of the underlying mechanisms. The current study combines neuroimaging and linguistic measures to unpack neurocognitive and psychological mechanisms associated with counterarguing among a sample of established smokers in response to anti-smoking messaging. We capture participants' neural activity in brain regions associated with effortful deliberation and negative argumentation during message exposure, and link it with their subsequent language patterns to further understanding of counterarguing in the brain. Greater brain activity within key regions of interest associated with deliberation and negative argumentation is associated with greater cognitive depth and less positivity in the post-scan message descriptions, respectively, among those who have lower intention to change their smoking behavior. We connect these neural representations of counterarguing with psychological theories and discuss implications that may increase the impact of persuasive communications.
Project description:Suicidal ideation (SI) is prevalent among individuals at clinical high-risk for psychosis (CHR). Natural language processing (NLP) provides an efficient method to identify linguistic markers of suicidality. Prior work has demonstrated that an increased use of "I", as well as words with semantic similarity to "anger", "sadness", "stress" and "lonely", are correlated with SI in other cohorts. The current project analyzes data collected in an SI supplement to an NIH R01 study of thought disorder and social cognition in CHR. This study is the first to use NLP analyses of spoken language to identify linguistic correlates of recent suicidal ideation among CHR individuals. The sample included 43 CHR individuals, 10 with recent suicidal ideation and 33 without, as measured by the Columbia-Suicide Severity Rating Scale, as well as 14 healthy volunteers without SI. NLP methods include part-of-speech (POS) tagging, a GoEmotions-trained BERT Model, and Zero-Shot Learning. As hypothesized, individuals at CHR for psychosis who endorsed recent SI utilized more words with semantic similarity to "anger" compared to those who did not. Words with semantic similarity to "stress", "loneliness", and "sadness" were not significantly different between the two CHR groups. Contrary to our hypotheses, CHR individuals with recent SI did not use the word "I" more than those without recent SI. As anger is not characteristic of CHR, findings have implications for the consideration of subthreshold anger-related sentiment in suicidal risk assessment. As NLP is scalable, findings suggest that language markers may improve suicide screening and prediction in this population.