Neural Correlates of Syntactic Comprehension: A Longitudinal Study

Broca’s area is frequently implicated in sentence comprehension but its specific role is debated. Most lesion studies have investigated deficits at the chronic stage. We aimed (1) to use acute imaging to predict which left hemisphere stroke patients will recover sentence comprehension; and (2) to better understand the role of Broca’s area in sentence comprehension by investigating acute deficits prior to functional reorganization. We assessed comprehension of canonical and noncanonical sentences in 15 patients with left hemisphere stroke at acute and chronic stages. LASSO regression was used to conduct lesion symptom mapping analyses. Patients with more severe word-level comprehension deficits and a greater proportion of damage to supramarginal gyrus and superior longitudinal fasciculus were likely to experience acute deficits prior to functional reorganization. Broca’s area was only implicated in chronic deficits. We propose that when temporoparietal regions are damaged, intact Broca’s area can support syntactic processing after functional reorganization occurs

Factors shaping the evolution of electronic documentation systems

The main goal is to prepare the space station technical and managerial structure for likely changes in the creation, capture, transfer, and utilization of knowledge. By anticipating advances, the design of Space Station Project (SSP) information systems can be tailored to facilitate a progression of increasingly sophisticated strategies as the space station evolves. Future generations of advanced information systems will use increases in power to deliver environmentally meaningful, contextually targeted, interconnected data (knowledge). The concept of a Knowledge Base Management System is emerging when the problem is focused on how information systems can perform such a conversion of raw data. Such a system would include traditional management functions for large space databases. Added artificial intelligence features might encompass co-existing knowledge representation schemes; effective control structures for deductive, plausible, and inductive reasoning; means for knowledge acquisition, refinement, and validation; explanation facilities; and dynamic human intervention. The major areas covered include: alternative knowledge representation approaches; advanced user interface capabilities; computer-supported cooperative work; the evolution of information system hardware; standardization, compatibility, and connectivity; and organizational impacts of information intensive environments

"Scholarly Hypertext: Self-Represented Complexity"

Scholarly hypertexts involve argument and explicit selfquestioning, and can be distinguished from both informational and literary hypertexts. After making these distinctions the essay presents general principles about attention, some suggestions for self-representational multi-level structures that would enhance scholarly inquiry, and a wish list of software capabilities to support such structures. The essay concludes with a discussion of possible conflicts between scholarly inquiry and hypertext

What does semantic tiling of the cortex tell us about semantics?

Recent use of voxel-wise modeling in cognitive neuroscience suggests that semantic maps tile the cortex. Although this impressive research establishes distributed cortical areas active during the conceptual processing that underlies semantics, it tells us little about the nature of this processing. While mapping concepts between Marr's computational and implementation levels to support neural encoding and decoding, this approach ignores Marr's algorithmic level, central for understanding the mechanisms that implement cognition, in general, and conceptual processing, in particular. Following decades of research in cognitive science and neuroscience, what do we know so far about the representation and processing mechanisms that implement conceptual abilities? Most basically, much is known about the mechanisms associated with: (1) features and frame representations, (2) grounded, abstract, and linguistic representations, (3) knowledge-based inference, (4) concept composition, and (5) conceptual flexibility. Rather than explaining these fundamental representation and processing mechanisms, semantic tiles simply provide a trace of their activity over a relatively short time period within a specific learning context. Establishing the mechanisms that implement conceptual processing in the brain will require more than mapping it to cortical (and sub-cortical) activity, with process models from cognitive science likely to play central roles in specifying the intervening mechanisms. More generally, neuroscience will not achieve its basic goals until it establishes algorithmic-level mechanisms that contribute essential explanations to how the brain works, going beyond simply establishing the brain areas that respond to various task conditions

Naturalistic language comprehension : a fMRI study on semantics in a narrative context

Semantiikka tutkii kieleen sisältyviä merkityksiä, joita tarvitaan kielen ymmärryksessä. Kuinka aivomme käsittelevät semantiikkaa ja kuinka ymmärrämme erityisesti luonnollisessa muodossa olevaa kieltä, on vielä aivotutkijoille epäselvää. Tässä tutkimuksessa kysyttiin, miten laajemmassa kontekstissa, narratiivissa, olevan kielen ymmärrys ja semanttinen prosessointi heijastuu aivojen aktiivisuuteen. Koehenkilöt kuulivat narratiivin toiminnallisen magneettiresonanssikuvantamisen (fMRI) aikana. Narratiivin semanttinen sisältö mallinnettiin laskennallisesti word2vec algoritmin avulla, ja tätä mallia verrattiin veren happitasosta riippuvaiseen (BOLD) aivosignaaliin ridge regression avulla vokseli kerrallaan. Lähestymistavalla saatiin eristettyä yksityiskohtaisempaa tietoa jatkuvan stimuluksen aivodatasta perustuen kielen semanttiseen sisältöön. Subjektien välinen BOLD-signaalin korrelaatio (ISC) itsessään paljasti molempien aivopuoliskojen osallistuvan kielen ymmärrykseen laajasti. Alueellista päällekkäisyyttä löytyi muiden aivoverkostojen kanssa, jotka vastaavat mm. mentalisaatiosta, muistista ja keskittymiskyvystä, mikä viittaa kielen ymmärryksen vaativan myös muiden kognition osien toimintaa. Ridge regression tulokset viittaavat bilateraalisten pikkuaivojen, superiorisen, keskimmäisen sekä mediaalisen etuaivokuoren poimujen, inferiorisen ja mediaalisen parietaalikuoren sekä visuaalikuoren, sekä oikean temporaalikuoren osallistuvan narratiivin semanttiseen prosessointiin aivoissa. Aiempi semantiikan tutkimus on tuottanut samankaltaisia tuloksia, joten word2vec vaikuttaisi tämän tutkimuksen perusteella mallintavan semantiikkaa riittävän hyvin aivotutkimuksen tarpeisiin. Tutkimuksen perusteella molemmat aivopuoliskot osallistuvat kielen laajemman kontekstin käsittelyyn, ja semantiikka nähdään aktivaationa eri puolilla aivokuorta. Nämä aktiivisuudet ovat mahdollisesti riippuvaisia kielen sisällöstä, mutta miten paljon kielen sisältö vaikuttaa eri aivoalueiden osallistumiseen kielen semanttisessa prosessoinnissa, on vielä avoin tutkimuskysymys.Semantics is a study of meaning in language and basis for language comprehension. How these phenomena are processed in the brain is still unclear especially in naturalistic context. In this study, naturalistic language comprehension, and how semantic processing in a narrative context is reflected in brain activity were investigated. Subjects were measured with functional magnetic resonance imaging (fMRI) while listening to a narrative. The semantic content of the narrative was modelled computationally with word2vec and compared to voxel-wise blood-oxygen-level dependent (BOLD) brain signal time courses using ridge regression. This approach provides a novel way to extract more detailed information from the brain data based on semantic content of the stimulus. Inter-subject correlation (ISC) of voxel-wise BOLD signals alone showed both hemispheres taking part in language comprehension. Areas involved in this task overlapped with networks of mentalisation, memory and attention suggesting comprehension requiring other modalities of cognition for its function. Ridge regression suggested cerebellum, superior, middle and medial frontal, inferior and medial parietal and visual cortices bilaterally and temporal cortex on right hemisphere having a role in semantic processing of the narrative. As similar results have been found in previous research on semantics, word2vec appears to model semantics sufficiently and is an applicable tool in brain research. This study suggests contextual language recruiting brain areas in both hemispheres and semantic processing showing as distributed activity on the cortex. This activity is likely dependent on the content of language, but further studies are required to distinguish how strongly brain activity is affected by different semantic contents

Common and distinct lateralised patterns of neural coupling during focused attention, open monitoring and loving kindness meditation

Meditation has been integrated into different therapeutic interventions. To inform the evidence-based selection of specific meditation types it is crucial to understand the neural processes associated with different meditation practices. Here we explore commonalities and differences in electroencephalographic oscillatory spatial synchronisation patterns across three important meditation types. Highly experienced meditators engaged in focused attention, open monitoring, and loving kindness meditation. Improving on previous research, our approach avoids comparisons between groups that limited previous findings, while ensuring that the meditation states are reliably established. Employing a novel measure of neural coupling – the imaginary part of EEG coherence – the study revealed that all meditation conditions displayed a common connectivity pattern that is characterised by increased connectivity of (a) broadly distributed delta networks, (b) left-hemispheric theta networks with a local integrating posterior focus, and (c) right-hemispheric alpha networks, with a local integrating parieto-occipital focus. Furthermore, each meditation state also expressed specific synchronisation patterns differentially recruiting left- or right-lateralised beta networks. These observations provide evidence that in addition to global patterns, frequency-specific inter-hemispheric asymmetry is one major feature of meditation, and that mental processes specific to each meditation type are also supported by lateralised networks from fast-frequency bands

Constructing Datasets for Multi-hop Reading Comprehension Across Documents

Most Reading Comprehension methods limit themselves to queries which can be answered using a single sentence, paragraph, or document. Enabling models to combine disjoint pieces of textual evidence would extend the scope of machine comprehension methods, but currently there exist no resources to train and test this capability. We propose a novel task to encourage the development of models for text understanding across multiple documents and to investigate the limits of existing methods. In our task, a model learns to seek and combine evidence - effectively performing multi-hop (alias multi-step) inference. We devise a methodology to produce datasets for this task, given a collection of query-answer pairs and thematically linked documents. Two datasets from different domains are induced, and we identify potential pitfalls and devise circumvention strategies. We evaluate two previously proposed competitive models and find that one can integrate information across documents. However, both models struggle to select relevant information, as providing documents guaranteed to be relevant greatly improves their performance. While the models outperform several strong baselines, their best accuracy reaches 42.9% compared to human performance at 74.0% - leaving ample room for improvement.Comment: This paper directly corresponds to the TACL version (https://transacl.org/ojs/index.php/tacl/article/view/1325) apart from minor changes in wording, additional footnotes, and appendice