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PubMed2003

New terminology services based on term comparison using semantic definitions and similarity computation.

As medical information can be encoded within different terminological systems, terms comparison is an important issue to allow communication between applications. In description logics, terms are compared by the means of semantic definitions and subsumption relations. Similarity is also a convenient method for term comparison but is not supported by terminology servers which implement subsumption relations. We present new terminology services built on a semantic distance that could help for semantic mediation between medical applications ranging from semi-automatic encoders to data mining tools. These services are 1) comparison between terms 2) k-nearest-neighbors 3) support for concept coding 4) automatic generation of similarity tables 5) distance based queries 6) support for clustering.

Artificial Intelligence↗

PubMed2003

Coverage of oncology drug indication concepts and compositional semantics by SNOMED-CT.

OBJECTIVE: To evaluate SNOMED-CT 's ability to represent simple and compositional concepts in FDA approved oncology drug indications. METHODS: Oncology drug indications were decomposed into single and compositional concepts. SNOMED-CT's coverage of single concepts and the semantics needed to create compositional concepts were evaluated using automated and manual techniques. RESULTS: SNOMED-CT covered 86.3% of single concepts present in oncology drug indications; 11.3% of indications were covered completely. Coverage was best for concepts describing diseases, anatomy, and patient characteristics. Medications accounted for 50.5% of missing concepts. Excluding drug names, 45.2% of indications were completely represented. SNOMED-CT's semantics completely represented 60.1% of compositional expressions. CONCLUSIONS: SNOMED-CT's overall coverage of the concepts in oncology drug indications was good. Improvements or alternatives are needed for medications and semantics.

Antineoplastic Agents↗

PubMed2004

Semantics and N400: insights for schizophrenia.

Thought disorder is a hallmark symptom of schizophrenia, which often leads to deficits in social functioning. Some aspects of this cognitive dysfunction are the result of abnormal characteristics in the semantic processes of patients. These abnormalities exist not only at the discourse production level, but at the discourse comprehension level as well. The recording and analysis of event-related potentials has greatly advanced the investigation of the processing of linguistic information. One particular component of event-related potentials, N400, indexes semantic processing. Whereas all meaningful words elicit an N400, the amplitude of this component is much greater in response to words that are unexpected in a given context. As such, it is thought to reflect processes involved in contextual integration, which is the key to correct comprehension. N400 has been found to be abnormal in patients with schizophrenia when compared with healthy controls and, thus, may point toward the underlying cause of semantic deficits of patients with thought disorder.

Cognition Disorders↗

PubMedDate not supplied

[Event related brain potentials and imageability effect in the semantic processing].

INTRODUCTION: Event-related brain potentials (ERPs) are a useful measure of the brain activity underlying linguistic processing. They can also be used to study cognitive/linguistic impairment in different neurological diseases. To do this, it is necessary to know which electrophysiological components are related to relevant linguistic parameters, and the characteristics of these components. One of these parameters is the dimension of concrete-abstract or imageability. AIM: To find electrophysiological evidence for differential processing of concrete vs abstract verbal material, in the absence of brain damage. SUBJECTS AND METHODS: The short, semantically congruent sentences used were made up of high or low imageability (HI/LI) verbs followed by HI/LI complements. We also manipulated close probability in the case of the complement. Sentences were shown word by word and participants were asked to make an imageability judgement. Electrophysiological recording during verb and final complement were analysed in ten subjects. RESULTS: Electrophysiological recording obtained during verb presentation show an imageability effect starting at 350 ms (especially in the N400 component) with no differential scalp distribution. There is a similar tendency in the recordings of final complements, although differences in imageability are not statistically significant. CONCLUSIONS: These results suggest the existence of an imageability effect in the ERPs associated with semantic processing in semantically congruent sentences and that this effect is produced when the verb is presented.

Adult↗

PubMed2005

Semantic integration in healthcare networks.

A seamless support of information flow for increasingly distributed healthcare processes requires to integrate heterogeneous IT systems into a comprehensive distributed information system. Different standards contribute to ease this integration. In a research project focussing on the development of a reference architecture for inter-institutional health information systems, we identified and categorised concurring integration standards by distinguishing between technical and semantic integration on the one hand, and data and functional integration on the other hand. In addition, standards for semantic integration are roughly categorised according to their scope. By placing standards into a corresponding matrix a "semantic gap" is revealed, which cannot be covered by standards as it contains volatile medical concepts. As a conclusion, it is recommended to conceptually consider the necessity of system evolution in systems architectures and also in future integration standards.

Computer Communication Networks↗

PubMed2006

An introduction to the Semantic Web for health sciences librarians.

OBJECTIVES: The paper (1) introduces health sciences librarians to the main concepts and principles of the Semantic Web (SW) and (2) briefly reviews a number of projects on the handling of biomedical information that uses SW technology. METHODOLOGY: The paper is structured into two main parts. "Semantic Web Technology" provides a high-level description, with examples, of the main standards and concepts: extensible markup language (XML), Resource Description Framework (RDF), RDF Schema (RDFS), ontologies, and their utility in information retrieval, concluding with mention of more advanced SW languages and their characteristics. "Semantic Web Applications and Research Projects in the Biomedical Field" is a brief review of the Unified Medical Language System (UMLS), Generalised Architecture for Languages, Encyclopedias and Nomenclatures in Medicine (GALEN), HealthCyberMap, LinkBase, and the thesaurus of the National Cancer Institute (NCI). The paper also mentions other benefits and by-products of the SW, citing projects related to them. DISCUSSION AND CONCLUSIONS: Some of the problems facing the SW vision are presented, especially the ways in which the librarians' expertise in organizing knowledge and in structuring information may contribute to SW projects.

Humans↗

PubMed2005

Towards semantic role labeling & IE in the medical literature.

INTRODUCTION: In this work, we introduce the concept of semantic role labeling to the medical domain. We report first results of porting and adapting an existing resource, Propbank, to the medical field. Propbank is an adjunct to Penn Treebank that provides semantic annotation of predicates and the roles played by their arguments. The main aim of this work is the applicability of the Propbank frame files to predicates typically encountered in the medical literature. METHODS: We analyzed a target corpus of 610,100 abstracts, which was selected by searching for publication type "case reports". From this target corpus, we randomly selected 10,000 sample abstracts to estimate the predicate distribution, and matched the predicates from this sample to the predicates in Propbank. RESULTS: Of the 1998 unique verbs in our sample, 76% were represented in Propbank. This included the 40 most frequent verbs, which represented 49% of all predicate instances in our sample and which matched the Propbank usage in a study of representative sentences. We propose extensions to Propbank that handle medical predicates, which are not adequately covered by Propbank. CONCLUSION: We believe that semantic role labeling using Propbank is a valid approach to capture predicate relations in the medical literature.

Abstracting and Indexing↗

PubMed1990

Semantic memory deterioration in Alzheimer's subjects: evidence from word association, definition, and associate ranking tasks.

The nature of semantic memory impairment in 23 persons with dementia of the Alzheimer type (DAT) was studied using three semantic tasks: word association, definition, and associate rank ordering. Using hierarchical log-linear analysis of the responses to the word association task, DAT subjects were more likely than normal control subjects to give multiword, repetitious, or unrelated responses. Additionally, the ratio of paradigmatic to syntagmatic responses was significantly decreased in DAT subjects. Surprisingly, DAT subjects were able to provide definitions for many stimulus words for which they were unable to provide meaningful associates. This finding suggests the need for caution in interpreting a decrease in the number of paradigmatic responses as indicative of a loss of conceptual knowledge. Results of other analyses demonstrated that DAT subjects had significant impairment in identifying highly related and unrelated semantic associates of words. Taken together, results of this study indicate that one feature of DAT is deterioration in the associative relations between concepts.

Alzheimer Disease↗

PubMedDate not supplied

Visual word perception and semantic processing: an electrophysiological perspective.

This paper reports data from three experiments in which semantic priming effects were investigated using the event-related potentials (ERP) technique. In the first experiment, a specific electrophysiological manifestation of semantic priming was demonstrated, and it was related to a previously reported negative component--N400. In the second experiment, it was suggested that the N400 wave does not directly reflect disconfirmation of subjects' expectations, but that it is related to semantic activation and is affected by the amount of lexical processing. In the third experiment, it was demonstrated that priming effects are also evident in natural reading, without any time constraints imposed by the task. It is concluded that the ERP technique provides an important tool in cognitive research in general, and language processing in particular.

Brain↗

PubMed1983

Semantic processing and recall improvement of EMR adolescents.

Semantic processing, in the form of stories linking to-be-remembered words, was compared with cumulative rehearsal in a free-recall task. Educable mentally retarded adolescents were either taught to generate a story, provided with a story, taught to rehearse cumulatively, or assigned to no-strategy control groups. Semantic-processing subjects showed better recall at original learning and, to a lesser extent, at a 20-week retention test. Results were discussed with reference to the mechanism of recall improvement and the generalizability of semantic training to a diversity of tasks.

Adolescent↗

PubMed1978

Category structure and semantic priming in retarded adolescents.

This study was designed to investigate the internal structure of semantic categories in mentally retarded adolescents as reflected in naming times to pictures of common objects. Pictures were presented in pairs that consisted of either categorically related or unrelated items. For related pairs, both the primes (first pictures) and targets (second pictures) varied in rated "typicality" (Rosch, 1975), being either typical or relatively atypical members of their primary superordinate category. An analysis of naming times to targets revealed a semantic-priming effect; targets in related pairs were named faster than those in unrelated pairs. Of major importance was the finding that naming times varied as a function of both prime typicality and target typicality. The data suggest that the semantic categories of retarded persons have an internal structure generally similar to that of the nonretarded persons from whom the typicality ratings were obtained and that even relatively atypical exemplars are functional category members for retarded persons.

Adolescent↗

PubMed1982

Episodic and semantic memory in posthypnotic amnesia: A reevaluation.

Recently, Kihlstrom found that a suggestion for posthypnotic amnesia produced impairments on episodic but not semantic memory tasks. During amnesia testing, highly and very highly susceptible subjects showed reduced recall for a previously learned word list but no deficits on a word association task designed to elicit the forgotten words as associates. He hypnotized that posthypnotic amnesia involved a dissociation between episodic and semantic components of memory. We tested the alternative hypothesis that Kihlstrom's findings resulted from experimental demands conveyed by the wording of the amnesia suggestion he employed. We found that subjects could be induced to show only episodic impairments (thereby replicating Kihlstrom) or both episodic and semantic impairments (contrary to Kihlstrom) by subtly varying the wording of amnesia suggestions. These findings are inconsistent with a dissociation hypothesis. Instead, they support the notion that hypnotic amnesia is a strategic enactment strongly influenced by expectations generated in the amnesia testing situation.

Adult↗

PubMed1995

A semantic network model for the medical record of a rheumatology clinic.

For the development of a rheumatology information system, a medical data dictionary was developed that supports all phases of software development. In the design phase, the medical expert described his clinical environment and the rheumatology medical record in a semantic network structure. Causal relationships between different items of the medical record (e.g., a problem may be related to an adverse drug event caused by a particular drug) are also represented in the semantic network and transferred into referential integrity constraints of the patient database. Furthermore, by also integrating the domain management as a feature of the medical data dictionary, the elementary attributes of the medical record and the associated lists of valid attribute entries have also been defined within the semantic network. This structure allowed the automatic generation of data entry screens, thus making the clinical applications as independent from any hardcoded program module as possible.

Algorithms↗

PubMed1997

Corpus-based identification and refinement of semantic classes.

Medical Language Processing (MLP), especially in specific domains, requires fine-grained semantic lexica. We examine whether robust natural language processing tools used on a representative corpus of a domain help in building and refining a semantic categorization. We test this hypothesis with ZELLIG, a corpus analysis tool. The first clusters we obtain are consistent with a model of the domain, as found in the SNOMED nomenclature. They correspond to coarse-grained semantic categories, but isolate as well lexical idiosyncrasies belonging to the clinical sub-language. Moreover, they help categorize additional words.

Classification↗

PubMed1998

Evaluation of a semantic data model for chest radiology: application of a new methodology.

An essential step toward the effective processing of the medical language is the development of representational models that formalize the language semantics. These models, also known as semantic data models, help to unlock the meaning of descriptive expressions, making them accessible to computer systems. The present study tries to determine the quality of a semantic data model created to encode chest radiology findings. The evaluation methodology relied on the ability of physicians to extract information from textual and encoded representations of chest X-ray reports, whilst answering questions associated with each report. The evaluation demonstrated that the encoded reports seemed to have the same information content of the original textual reports. The methodology generated useful data regarding the quality of the data model, demonstrating that certain segments were creating ambiguous representations and that some details were not being represented.

Adult↗

PubMed1998

Beyond synonymy: exploiting the UMLS semantics in mapping vocabularies.

The Unified Medical Language System (UMLS) contains semantic information about terms from various sources, each concept can be understood and located by its relationships to other concepts: this is a result of the organizing principle of semantic locality. We describe a method in which the semantic relationships between concepts are used to map concepts from different vocabularies in the UMLS. Applied to mapping concepts to MeSH, this method is able to map 50 to 65% of the non-MeSH concepts to MeSH. A manual review of the mapping shows a relevance rate of 61%. Causes of failure include a lack of consistently represented relationships in the UMLS, and some inconsistencies in the categorization of the concepts. The limits of this method are discussed, as well as possible adaptations for other uses.

Algorithms↗

PubMed1998

Automatic semantic interpretation of anatomic spatial relationships in clinical text.

A set of semantic interpretation rules to link the syntax and semantics of locative relationships among anatomic entities was developed and implemented in a natural language processing system. Two experiments assessed the ability of the system to identify and characterize physico-spatial relationships in coronary angiography reports. Branching relationships were by far the most common observed (75%), followed by PATH (20%) and PART/WHOLE relationships. Recall and precision scores were 0.78 and 0.67 overall, suggesting the viability of this approach in semantic processing of clinical text.

Anatomy↗

PubMed1986

Semantic and visual memory after alcohol abuse.

This study compared the relative performance of 40 patients (M age = 31.7) with a history of alcohol abuse on tasks of short-term semantic and visual memory. Performance on the visual memory tasks was impaired significantly relative to the semantic memory task in a within-subjects analysis of variance. Semantic memory was unimpaired. This result is consistent with previous results obtained on tests of intelligence despite the added requirement of encoding, storing, and retrieving data inherent in the memory tasks. This result provides support for the contention that visuospatial and visuomotor skills evince primary residual impairment secondary to the abuse of alcohol. The significance of this result, in light of previous research, is discussed.

Adult↗