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PubMed2005

Indexing UMLS Semantic Types for Medical Question-Answering.

Open-domain Question-Answering (QA) systems heavily rely on named entities, a set of general-purpose semantic types which generally cover names of persons, organizations and locations, dates and amounts, etc. If we are to build medical QA systems, a set of medically relevant named entities must be used. In this paper, we explore the use of the UMLS (Unified Medical Language System) Semantic Network semantic types for this purpose. We present an experiment where the French part of the UMLS Metathesaurus, together with the associated semantic types, is used as a resource for a medically-specific named entity tagger. We also explore the detection of Semantic Network relations for answering specific types of medical questions. We present results and evaluations on a corpus of French-language medical documents that was used in the EQueR Question-Answering evaluation forum. We show, using statistical studies, that strategies for using these new tags in a QA context are to take in account the individual origin of documents.

Humans↗

PubMed2006

[Semantic extension to DICOM standard].

The Digital Imaging and Communications in Medicine (DICOM) Standard was developed by National Electrical Manufacturers Association (NEMA) and the American College of Radiology (ACR) for medical image archiving and communication. The Standard is widely used in medicine now. But it does not define image semantic content sufficiently, so there is a difficulty in the implementation based on semantic content. In this article are discussed the semantic hierarchy structure in medical image and the method to describe the image content used in the DICOM Standard. We point out the limitations of DICOM in image semantic content description, and then set forth a way to extend the semantic content description by using DICOM private attributes.

Computer Communication Networks↗

PubMed2006

Semantic interoperability--HL7 Version 3 compared to advanced architecture standards.

OBJECTIVES: To meet the challenge for high quality and efficient care, highly specialized and distributed healthcare establishments have to communicate and co-operate in a semantically interoperable way. Information and communication technology must be open, flexible, scalable, knowledge-based and service-oriented as well as secure and safe. METHODS: For enabling semantic interoperability, a unified process for defining and implementing the architecture, i.e. structure and functions of the cooperating systems' components, as well as the approach for knowledge representation, i.e. the used information and its interpretation, algorithms, etc. have to be defined in a harmonized way. Deploying the Generic Component Model, systems and their components, underlying concepts and applied constraints must be formally modeled, strictly separating platform-independent from platform-specific models. RESULTS: As HL7 Version 3 claims to represent the most successful standard for semantic interoperability, HL7 has been analyzed regarding the requirements for model-driven, service-oriented design of semantic interoperable information systems, thereby moving from a communication to an architecture paradigm. The approach is compared with advanced architectural approaches for information systems such as OMG's CORBA 3 or EHR systems such as GEHR/openEHR and CEN EN 13606 Electronic Health Record Communication. CONCLUSION: HL7 Version 3 is maturing towards an architectural approach for semantic interoperability. Despite current differences, there is a close collaboration between the teams involved guaranteeing a convergence between competing approaches.

Computer Communication Networks↗

PubMedDate not supplied

Semantic relations of the word in aphasics.

The study of the semantic relations of the word in aphasics was performed by an associative experiment applied in two samples, one of 20 aphasic patients and the other of 40 normal subjects. Following application of this associative experiment in normal subjects, a model design was achieved based on the hierarchy of the categories within the semantic field. In this model, the associations were grouped by meaning into semantic categories, while the categories were hierarchized according to the number of words included and to their frequency of association. Comparison of the single model design performed by each aphasic with the normal model design showed a deterioration of the semantic categories, hierarchy, but on a background of a marked reduction of the number of categories within the semantic field of the stimulus. The aphasics lost 2/3 of the associations found in normals but the functionality of the 1/3 left was decreased. This may be the basic reason for the unsuccessful word-finding process in aphasics.

Adult↗

PubMed2006

Knowledge acquisition for computation of semantic distance between WHO-ART terms.

Computation of semantic distance between adverse drug reactions terms may be an efficient way to group related medical conditions in pharmacovigilance case reports. Previous experience with ICD-10 on a semantic distance tool highlighted a bottleneck related to manual description of formal definitions in large terminologies. We propose a method based on acquisition of formal definitions by knowledge extraction from UMLS and morphosemantic analysis. These formal definitions are expressed with SNOMED International terms. We provide formal definitions for 758 WHO-ART terms: 321 terms defined from UMLS, 320 terms defined using morphosemantic analysis and 117 terms defined after expert evaluation. Computation of semantic distance (e.g. k-nearest neighbours) was implemented in J2EE terminology services. Similar WHO-ART terms defined by automated knowledge acquisition and ICD terms defined manually show similar behaviour in the semantic distance tool. Our knowledge acquisition method can help us to generate new formal definitions of medical terms for our semantic distance terminology services.

Adverse Drug Reaction Reporting Systems↗

PubMed1984

Semantic desensitization: a paradigmatic intervention approach to anxiety disorders.

Studied the effectiveness of semantic desensitization in alleviating public speaking anxiety. Thirty speech-anxious clients, matched on the severity of their problem, were assigned randomly to one of the following treatment conditions: (a) semantic desensitization; (b) attention placebo; and (c) waiting list control. The semantic desensitization group received a self-instructional, anticipatory-anxiety hierarchy paired with visually induced, relaxing, pleasant scenes. Semantic desensitization therapy resulted in significant reductions of both the affective and behavioral components of anxiety as compared to the two controls. The placebo control also showed improvement in several indices of subjective anxiety as compared to the no-treatment waiting list control. The beneficial effects of semantic desensitization therapy were maintained on follow-up.

Anxiety Disorders↗

PubMed1981

Semantic and contextual cuing of preschool children's recall.

3 experiments were carried out to investigate cuing of young children's recall. In each experiment younger (3 years) and older (4 1/2 years) preschool children were tested on free and cued recall tasks in which the presence of semantic and contextual cues was manipulated. In the first 2 experiments there was little evidence that the children's recall was facilitated by presence of contextual cues, independent of the facilitation produced by semantic information. In the third experiment, context and target items were integrated experimentally at presentation. In this case, unrelated context cues improved recall. This finding suggests that limitations in the facilitatory effects of context cues for preschool children are related to the ways these young children initially encode target and context items. In all 3 experiments semantic cues aided both younger and older children's recall. Moreover, there was evidence of a developmental increase in the effectiveness of semantic, but not contextual, cues. This finding highlights the importance of growth of the semantic knowledge base for early memory development.

Child Development↗

PubMed1980

Life-span differences in semantic integration of pictures and sentences in memory.

This study examined life-span developmental differences in spontaneous integration of semantically relevant material presented in pictures and sentences. 45 third graders, 45 sixth graders, 45 high school students, and 30 adults over 60 were presented a sequence of 24 pictures and sentences, followed by 24 intervening items. Each intervening item corresponded to, but was in the opposite modality from, one of the original items and was either semantically relevant or irrelevant to the corresponding original. In a "same-different" recognition test, data suggested that the sixth-grade and high school subjects semantically integrated original items with relevant intervening items that were in the opposite modality and made subsequent recognition responses on the basis of the integrated memory. Third graders and older adults, however, showed no evidence of spontaneous, cross-modality semantic integration. Further, increasing the temporal delay between presenting the to-be-integrated items, from 5 min to 1 day, decreased overall response sensitivity but did not alter the patterns of integration results. The findings are discussed in terms of age differences in the spontaneous use of strategies for effective memory processing, with the extreme age groups processing more formal characteristics of the stimuli in memory, and the middle 2 groups processing deeper, more semantic information.

Adolescent↗

PubMed1993

Semantic relations as graded concepts.

This experiment tests the hypothesis that semantic relations are graded concepts. It also tests the predictions of relation element theory and of Klix's (1986) theory of semantic relations regarding possible predictors of graded structure for semantic relations. Results support the hypothesis that semantic relations have graded structures, and indicate that differences among relations in gradedness reflect the families of semantic relations described by Chaffin & Herrmann (1984). In addition, Klix's distinction between property relations and event relations appears to be useful in explaining differences among relations in graded structure.

Concept Formation↗

PubMed1993

[Semantic information. Internal language. Thinking].

Semantic information has reached an objective condition after a lengthy history of semantic inquiries that instrumental neurophysiological devices--such as event-related potentials, electroencephalographic spectral analysis, regional brain circulation, PET scan, deep brain electrodes, and other--have made easier. In turn, internal language, as screened according to Vigotsky's perspective, is considered a product of semantic information circulation understood as neurosemae interconnection. Finally, in normal adults, thinking processes are assumed to be made up by both sensoperceptive information (proprioceptive information included) and semantic information. Thus, an "extraverbal thinking" can be distinguished, whose activity is hardly describable in healthy adults but should be considered as a condition of non-educated deaf persons, and a "verbal thinking", or internal language, made up by semantic information.

Humans↗

PubMed1995

Enhancing medical database semantics.

Medical Databases deal with dynamic, heterogeneous and fuzzy data. The modeling of such complex domain demands powerful semantic data modeling methodologies. This paper describes GSM-Explorer a Case Tool that allows for the creation of relational databases using semantic data modeling techniques. GSM Explorer fully incorporates the Generic Semantic Data Model-GSM enabling knowledge engineers to model the application domain with the abstraction mechanisms of generalization/specialization, association and aggregation. The tool generates a structure that implements persistent database-objects through the automatic generation of customized SQL ANSI scripts that sustain the semantics defined in the higher lever. This paper emphasizes the system architecture and the mapping of the semantic model into relational tables. The present status of the project and its further developments are discussed in the Conclusions.

Information Systems↗

PubMed1977

Adult aphasics: relationship between convergent and divergent semantic behavior.

The purpose of the present study was to empirically evaluate the relationship between the ability of 30 aphasic subjects to produce a number and a variety of semantic responses with their ability to produce highly, knowledge-oriented, automatic responses. That is, the relationship between divergent and convergent semantic behaviors was explored. Use of both types of tasks will more adequately reflect the semantic strategies needed for spontaneous communication in day-to-day life situations. Results of the present study show that divergent and convergent behavior seem to require separate and distinct abilities for aphasic subjects. The strong and significant correlations between subject performance on the verbal, gestural and graphic convergent variables and subject ability to produce a number and a variety of relevant semantic responses confirms the fact that aphasia is both a divergent and a convergent semantic disorder. The findings of the present study therefore indicate the need to create diagnostic and therapeutic paradigms with divergent tasks that emphasize a variety, quantity and relevance of output from the same source, as well as the more traditional convergent tasks that are more highly knowledge oriented.

Adult↗

PubMed1997

Semantic priming impairment in HIV.

HIV+ subjects have shown impairment on tests of executive function including automatic attention and verbal tasks. Impairment of semantic priming in HIV patients would suggest a disruption of automatic semantic activation. We examined semantic priming in HIV+ individuals and HIV- control participants with no history of substance abuse, neurologic or psychiatric disorder unrelated to HIV. HIV+ participants were divided into cognitively normal and cognitively impaired subgroups on the basis of a neuropsychological battery of 15 tests. Participants were presented with English words and nonword letter strings and indicated if the stimulus was a word or nonword. The nonwords were orthographically and phonologically correct and were created by rearranging the letter sequence of words ("ulpit"). All words had an obvious antonym ("deep"); two-thirds were presented as sequential antonym pairs ("enter"-"exit"). There were no group differences in speed of response to nonwords, indicating no generalized reaction time deficit. While control and cognitively normal HIV+ participants showed an effect of priming on reaction time to correctly detected words, cognitively impaired HIV+ participants did not. The lack of semantic priming demonstrated by cognitively impaired HIV+ participants suggests that they have lessened activation of automatic semantic networks.

Adult↗

PubMed1990

Delineation of single-word semantic comprehension deficits in aphasia, with anatomical correlation.

In 3 of 18 aphasic patients pure deficits in semantic comprehension at the single-word level were defined through a series of tasks that excluded possible confounding deficits in auditory perception, visual perception, or speech production. In these pure cases, deficits were found at the superordinate, equivalence, and subordinate levels of single-word semantic processing. Pure semantic deficits were found to be correlated with damage to the left posterior temporal and inferior parietal region; patients whose damage spared this area did not evince such deficits, and the converse was also true. This study confirms the existence of separable deficits in semantic comprehension and points conclusively to the left posterior temporal and inferior parietal region as being critical for semantic processing. This anatomical localization is in keeping with anatomical studies from nonhuman primates, suggesting that these regions may be concerned with multimodal processing and integration of language.

Aphasia↗

PubMed1998

ERP mapping in phonological and lexical semantic monitoring tasks: A study complementing previous PET results.

Previous PET results identified distinct neural systems involved with phonology (vicinity of the left sylvian fissure) and lexical semantics (left inferior temporal, left superior frontal, bilateral inferior parietal regions). In the time domain, the phonological task was thought to involve serial parsing of pseudo-words, whereas the lexical semantic task would correspond to probabilistic automated access to meaning. Auditory event-related potentials (ERPs) elicited by the same tasks were explored on 32 channels in 12 male volunteers. Subjects had to categorize as target a second element of a pair of pseudo-words or words if a preceding target was detected in the first element. Depending on the absence/presence of target in the first element, a RELEASE condition and a HOLD condition were distinguished. RELEASE and HOLD ERPs split earlier in the semantic task than in the phonological task (300 versus 412 ms after SOT, respectively), although words lasted longer than pseudo-words. Corresponding paired t test maps showed a predominance of differences over left perisylvian regions for the phonological task and posterior bilateral regions for the semantic task. Underlying generators were investigated using BESA (Scherg, 1990) with global task ERPs. Six dipoles-constrained according to PET clusters-brought residual variance down to 0.36%, from 364 to 565 ms after SOT, in both tasks. Relative dipole amplitudes suggested a left-sided functional asymmetry for phonology. These results support the hypothesis of left perisylvian serial processing for phonology contrasting with bihemispheric parallel access for semantics and substantiates BESA for temporally tackling cognitive processes.

Adult↗

PubMed2002

Frequency of concrete words modulates prefrontal activation during semantic judgments.

The effect of word frequency on semantic processing was characterized by studying two groups of right-handed participants using fMRI. Stimuli were presented in blocks of either high frequency or low frequency word triplets where a sample word appeared above a pair of test words. One group (n = 8) made semantic judgments by selecting the word from the test pair that was more closely associated with the sample. Stimulus triplets were designed such that relatedness between sample and "correct" items was obvious. The other group (n = 8) read the words silently without making any semantic decision and pressed a button on completing the reading of each triplet. Semantic judgments while no less accurate, were associated with greater left prefrontal BOLD signal change when they involved low frequency words, whereas there was no reliable effect of word frequency in the reading condition. These findings suggest that retrieval effort modulates left prefrontal activity when deliberate access to semantics is required.

Adult↗

PubMed2001

Syntactic and semantic processing in the healthy and aphasic human brain.

A syntactic and a semantic task were performed by German-speaking healthy subjects and aphasics with lesions in the dominant left hemisphere. In both tasks, pictures of objects were presented that had to be classified by pressing buttons. The classification was into grammatical gender in the syntactic task (masculine or feminine gender?) and into semantic category in the semantic task (man- or nature made?). Behavioral data revealed a significant Group by Task interaction, with aphasics showing most pronounced problems with syntax. Brain event-related potentials 300-600 ms following picture onset showed different task-dependent laterality patterns in the two groups. In controls, the syntax task induced a left-lateralized negative ERP, whereas the semantic task produced more symmetric responses over the hemispheres. The opposite was the case in the patients, where, paradoxically, stronger laterality of physiological brain responses emerged in the semantic task than in the syntactic task. We interpret these data based on neuro-psycholinguistic models of word processing and current theories about the roles of the hemispheres in language recovery.

Adult↗

PubMed1985

Event-related potentials, lexical decision and semantic priming.

ERPs were recorded during a lexical decision task in order to investigate electrophysiological concomitants of semantic priming. The stimuli were 240 words and 240 nonwords presented one per trial at a fixed intertrial interval. Subjects were required to classify each stimulus as a word or nonword by pressing one of two response buttons. ERPs were recorded from 14 scalp locations, the right suborbital ridge, and the left earlobe, all referred to a balanced non-cephalic reference. RT and error data confirmed that semantic priming occurred under the conditions employed: primed words (those preceded by a semantically related word) were identified as words faster and more accurately than were unprimed words (those preceded by semantically unrelated words or nonwords). ERPs for all stimulus types were characterized by a large positivity peaking between 550 and 650 msec, preceded by a negative-going deflection peaking at approximately 400 msec. ERPs for primed and unprimed words were shown to differ significantly, diverging 200-250 msec following stimulus onset, reaching a maximum near the peak of the negative-going deflection at 400 msec. These differences were observed at locations over both hemispheres and were maximal in the centroparietal region. Although P300 latency differences between primed and unprimed words were also obtained, the priming effect on ERPs at shorter latencies could not be explained solely by P300 latency effects. Possible relationships between these ERP concomitants of semantic priming and P300, N200, and N400 were discussed.

Adolescent↗