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PubMed2001

Consciousness in schizophrenia: a metacognitive approach to semantic memory.

Recent studies have shown that schizophrenia may be a disease affecting the states of consciousness. The present study is aimed at investigating metamemory, i.e., the knowledge about one's own memory capabilities, in patients with schizophrenia. The accuracy of the Confidence level (CL) in the correctness of the answers provided during a recall phase, and the predictability of the Feeling of Knowing (FOK) when recall fails were measured using a task consisting of general information questions and assessing semantic memory. Nineteen outpatients were paired with 19 control subjects with respect to age, sex, and education. Results showed that patients with schizophrenia exhibited an impaired semantic memory. CL ratings as well as CL and FOK accuracy were not significantly different in the schizophrenic and the control groups. However, FOK ratings were significantly reduced for the patient group, and discordant FOK judgments were also observed more frequently. Such results suggest that FOK judgments are impaired in patients with schizophrenia, which confirms that schizophrenia is an illness characterized by an impaired conscious awareness of one's own knowledge.

Adult↗

PubMed1998

Event-related brain potential imaging of semantic encoding during processing single words.

Functional brain imaging studies with positron emission tomography (PET) have identified blood flow changes in widely separated areas of brain during the performance of word processing tasks. In the present study we have utilized event-related brain potentials (ERPs) to investigate the temporal relationships among cortical areas previously identified by PET to be differentially activated when performing semantic tasks with visual words. ERPs revealed task-related differences over the central and left inferior frontal regions around 170 and 220 ms, respectively, over a left occipital region around 200 ms, over a large left parietotemporal region around 600 ms, and finally over the right temporal lobe around 800 ms after the word presentation. Analysis of topographic maps and dipole sources as well as PET data allowed relating frontal midline positivity around 170 ms to the anterior cingulate activation, and left inferior frontal positivity around 220 ms to the PET activation of the left inferior prefrontal cortex. The left parieto-temporal positivity around 600 ms seems to reflect the activity of Wernicke's area. The right anterior temporal negativity beginning around 800 ms and peaking around 1100 ms may reflect the activity of the right insula. The left occipital negativity around 200 ms is likely to reflect activation of a visual word-form area in the left occipital lobe. These results provide the time course for parts of the circuitry involved in semantic processing of words and also demonstrate how combining the spatial localization of PET with the temporal resolution of ERPs helps to understand the brain mechanisms involved in human cognition.

Adult↗

PubMed2000

Brain mechanisms for detecting perceptual, semantic, and emotional deviance.

The observation that we note the exceptional over the mundane has been the subject of extensive psychological and electrophysiological analysis in "oddball" paradigms. Whether detection of a sensory oddball reflects the operation of a generic mechanism or, alternatively, mechanisms sensitive to specific attributes of stimulus deviance is unknown. To address this question we used event-related functional MRI (fMRI) to measure neural responses during presentation of nouns, of which a proportion were perceptually, semantically, or emotionally deviant. Oddballs, regardless of deviant attributes and depth of processing, activated right inferior prefrontal and bilateral posterior fusiform cortices. Attribute-specific responses, independent of depth of processing, were evident in bilateral fusiform cortices for perceptual oddballs and left amygdala for emotional oddballs. By contrast, an interaction with depth of processing was evident in left prefrontal cortex for semantic oddballs. We conclude that detection of oddballs reflects the operation of a generic "deviance detection system," involving right prefrontal and fusiform cortices in addition to specific brain regions sensitive to the stimulus attributes that determine the qualitative characteristics of deviance.

Adolescent↗

PubMed2001

Relative language proficiency modulates BOLD signal change when bilinguals perform semantic judgments. Blood oxygen level dependent.

The effect of relative language proficiency on the spatial distribution and magnitude of BOLD signal change was evaluated by studying two groups of right-handed English-Mandarin bilingual participants with contrasting language proficiencies as they made semantic judgments with words and characters. Greater language proficiency corresponded to shorter response times and greater accuracy in the semantic judgment task. Within the left prefrontal and parietal regions, the change in BOLD signal was smaller in a participant's more proficient language. The least proficient performance was associated with right, in addition to left, inferior frontal activation. The results highlight the importance of taking into consideration nature of task and relative language proficiency when drawing inferences from functional imaging studies of bilinguals.

Adult↗

PubMed1991

The semantics of pain in Indian culture and medicine.

An interpretive perspective offers a counterpoint to the behavioral orientation in the social scientific literature on pain. The present paper develops a meaning-centered approach which focuses on three interconnected aspects of the experience of suffering: (1) the cultural construction of pain sensation; (2) the semiotics of pain expression; (3) the structure of pain's causes and cures. These connections are explored through a variety of linguistic and semiotic forms, including metaphors, etymologies, gestural codes, taxonomies, and semantic networks. The study of metaphor has special value in revealing the cultural construction of pain, especially its sensory qualities, such as temperature, weight, and movement. The concept of semantic network provides a complementary tool for understanding pain experience; the analysis makes pain sensation the center of the network and argues that multiple meanings attach to this sensory core. The paper examines these perspectives in the context of North Indian culture and medicine, specifically Unani Tibb, or Greco-Arab medicine. Pursuing questions of the "fit" between everyday belief and traditional medicine, the essay traces continuities in the "language of pain" in North Indian culture, classical Unani Tibb, and contemporary Unani clinical practice.

Cross-Cultural Comparison↗

PubMed1992

Autism by another name? Semantic and pragmatic impairments in children.

The literature on children with language disorders that are characterized by semantic and pragmatic impairments is reviewed and the conclusion is drawn that some of these conditions may stem from the same fundamental cognitive and interpersonal difficulties that are found in early childhood autism. A summary is presented of recent relevant research and theory in the field of autism and suggestions are offered on how these ideas might be applied to children showing semantic and pragmatic difficulties.

Autistic Disorder↗

PubMed1989

Lexical projection and the interaction of syntax and semantics in parsing.

A series of self-paced reading studies utilized an embedded anomaly technique to investigate long-distance dependencies with dative verbs. Previous research in our lab demonstrated that argument structure influences the gap-filling process. Experiment 1 extended that work by demonstrating that dative verbs pattern with other complex transitive verbs (i.e., a fronted filler that is implausible as the direct object will not be interpreted as the direct object until the absence of a noun phrase after the verb forces the postulation of a direct object gap. This pattern contrasts with that of transitive verbs that subcategorize for a single internal argument position, where fronted fillers are obligatorily interpreted as the direct object). Experiments 2 and 3 investigate the prediction that semantic analyses precede syntactic analyses in dative questions. It is argued that the lexical information about argument structure and thematic roles can guide semantic interpretation.

Adult↗

PubMed1989

Polysemy and the subjective lexicon: semantic relatedness and the salience of intraword senses.

Subjective perceptions of the senses of polysemous English words are collected in questionnaire studies and the effects of variability in semantic distances among these senses are examined in an experiment. In the first of two questionnaire studies, native speakers produce meanings for 175 polysemous words; from their responses, the most frequently produced meaning for each word is identified as its dominant sense. In a second questionnaire, independent subjects rate the semantic relatedness between the dominant meaning and the other senses generated for each word in the first study. Relatedness measures vary, raising the possibility that polysemous words vary in terms of the salience of their different senses in different contexts. This is confirmed in an experiment showing that salience ratings are influenced by the interacting factors of sentential context, extent of relatedness of the senses, and the dominance status of the senses.

Adolescent↗

PubMed1992

Naming disorders and semantic representations.

The status of semantic conceptual structures in aphasia was investigated with relation to naming disorders in spontaneous and constrained speech production. A battery of six tasks was administered to 25 control subjects and 25 aphasics: spontaneous speech production (from which the percentage of nouns was calculated), confrontation naming, understanding class relationships (verbal and pictorial), and understanding thematic relationships (verbal and pictorial). Results indicated the important role of taxonomic abilities for naming, while other conceptual structures (i.e., thematic relations) do not seem to play any important role in the process of naming. These results are discussed in terms of the internal organization of semantic information.

Adolescent↗

PubMed1990

A measure of semantic complexity among predications.

A scale for assessing the complexity or density of utterances was developed using 10 categories of semantic relations (e.g., temporal ordering, causality). The categories are inferable from the particular "meanings" of the words (e.g., connectives, particular tense variations) used in an utterance. The scale was applied to three samples of subjects to assess its interjudge reliability and to compare the utterances of fourth-, sixth-, and eighth-grade children from middle- and working-class neighborhoods. It was also used to compare the complexity of utterances for different types of visual stimuli (used to elicit language samples). Interjudge reliabilities were more than acceptable for each of the samples, and significant differences in semantic density were found across grade, between children from working-class and middle-class neighborhoods, and for the stimuli used to elicit the utterances. When two of the three types of eliciting visual stimuli were equated for content and exposure conditions, the differences in verbal density between eliciting conditions were not replicated. The usefulness of the scale for assessing utterance density and by implication, comprehension difficulty of utterances and of texts, is discussed.

Attention↗

PubMed1990

Psychobiological evidence for the distinction between episodic and semantic memory.

The evidence for discrete neurobiological mechanisms that underlie episodic and semantic memory is reviewed. Published data from three separate lines of research are considered: studies of human amnesic patients, psychopharmacological studies of normal human subjects, and studies of working and reference memory in rodents, a distinction that is arguably analogous to the episodic/semantic dichotomy. It is concluded that the available evidence does not indicate that episodic and semantic memory are mediated by discrete neural subsystems. An alternative model of human memory is discussed, based on the concept of parallel distributed processing.

Amnesia↗

PubMed1981

Developmental language disorders: cognitive processes, semantics, pragmatics, phonology, and syntax.

Five areas of research concerned with language acquisition--cognitive processes, semantics, pragmatics, phonology, and syntax--are reviewed in terms of their contribution to understanding language disorders. Two views of cognitive processes are discussed. One of these, emphasizing cognitive mechanisms such as short-term memory, is seen as providing possible explanations for some types of language deficits. The other, a concern with conceptual knowledge, is subjected to a critical analysis questioning how complete an explanation it is able to offer for some aspects of language acquisition. Problems of definition are also discussed when semantic aspects of language are considered. Problems in the pragmatic component of language are seen as providing an explanation for particular aspects of language disorder in some autistic children. The importance of focusing on phonology as a central grammatical process is discussed and linked to dyslexia and to spelling disorders. Finally, it is argued that the acquisition of syntactic structure is not yet understood. Impairments such as a hierarchical planning order deficit may affect syntactic ability and lead to disordered language, as found in some types of developmentally aphasic children. It is concluded that it is important to study all five areas of the title, and their interrelationships, if various language disorders are to be adequately understood.

Child, Preschool↗

PubMed2000

State-dependent effects of alcohol on explicit memory: the role of semantic associations.

RATIONALE: Memory performance can be facilitated when the context in which retrieval occurs matches the context in which learning initially took place in two separate ways, in form of interactive or independent context. In the present study, the differential effects of alcohol, as independent context, on the free recall of items of high or low semantic associations were investigated. The high and low associations offer different strengths of interactive context at stimulus input, i.e. context that influences what will be stored. METHODS: Using a state-dependent retrieval paradigm, alcohol (0.8 g/kg) or placebo was administered prior to encoding and/or retrieval and their effects were tested using measures of free recall. Forty-eight participants were tested according to a traditional state-dependent retrieval design where half of the subjects studied the items under alcohol (A), half under placebo (P) followed by retrieval of the items under A or P giving four groups (AA, AP, PA, PP). RESULTS: Delayed free recall was significantly impaired when alcohol was administered prior to both encoding and retrieval of study material (P<0.05). Alcohol administered prior to encoding and prior to retrieval decreased especially the recall of high association items (P<0.05). Participants in the same-state groups (AA, PP) recalled fewer low association items than participants in disparate state groups (AP, PA; P<0.05). This effect of drug state on low associations may reflect an inability of weaker cues to facilitate retrieval in the presence of stronger cues (i.e. high associations and drug). Indeed, participants in the same-state groups recalled a greater percentage of material in form of high association items than participants in disparate-state groups (P<0.05). CONCLUSIONS: These results demonstrate that alcohol given at encoding and at retrieval specifically impairs retrieval of high association items. However, if the drug state is the same at encoding and at retrieval, the items with the high associations represent a higher proportion of the total recalled items. These data suggest that alcohol may provide an internal context that can facilitate retrieval of information, acquired in semantic context, which otherwise would have been lost.

Adult↗

PubMed2005

Functional neuroanatomy of non-verbal semantic sound processing in humans.

Environmental sounds convey specific meanings and the neural circuitry for their recognition may have preceded language. To dissociate semantic mnemonic from sensory perceptual processing of non-verbal sound stimuli we systematically altered the inherent semantic properties of non-verbal sounds from natural and man-made sources while keeping their acoustic characteristics closely matched. We hypothesized that acoustic analysis of complex non-verbal sounds would be right lateralized in auditory cortex regardless of meaning content and that left hemisphere regions would be engaged when meaningful concept could be extracted. Using H(2) (15)O-PET imaging and SPM data analysis, we demonstrated that activation of the left superior temporal and left parahippocampal gyrus along with left inferior frontal regions was specifically associated with listening to meaningful sounds. In contrast, for both types of sounds, acoustic analysis was associated with activation of right auditory cortices. We conclude that left hemisphere brain regions are engaged when sounds are meaningful or intelligible.

Acoustic Stimulation↗

PubMed1999

Word-list learning in normally developing children: effects of semantic organization and retention interval.

Immediate and 15-min delayed recall of semantically related or unrelated word lists was investigated in 144 normally developing children ranging from 5 to 10 years of age. Immediate recall for the related and unrelated lists increased in a parallel fashion as a function of age. The ability to cluster semantically related items during immediate recall also improved with age. However, in no age class recall scores and clustering indexes were significantly associated. Forgetting rate passing from the last immediate to the delayed recall trial increased for the unrelated list but decreased for the related list of words as a function of age. Results of regression analyses revealed that a developmental increase in forgetting on the unrelated list was actually due to the higher number of words recalled in the last immediate trial by older children. As for the related list, instead, the larger reliance on the clustering strategy of recall by older children was responsible for the progressive reduction of forgetting.

Aging↗

PubMed2007

An electrophysiological investigation of semantic incongruity processing by people with Asperger's syndrome.

The aim of this study was to investigate whether a physiological measure of impaired use of context could be obtained in people with Asperger's Syndrome (AS). The experimental paradigm employed was the use of electroencephalography to measure the detection of semantic incongruity within written sentences, as indexed by an N400 event-related potential. Whilst the seven controls appropriately demonstrated N400 potentials only to semantically incongruent stimuli, the seven participants with AS inappropriately demonstrated N400 potentials to congruent stimuli. These results are compatible with the possibility that the participants with AS did not use the context within sentences to predict the final word of the sentences.

Adolescent↗

PubMed2005

Semantic and phonological processing in reading Korean Hangul and Hanja words.

The Korean orthography uses both alphabetic Hangul and logographic Hanja. Two experiments investigated semantic and phonological processing of words written in the two scripts. In the experiments, Korean readers had to respond to words either in a pure context with words from one single script or in a mixed context with words from the two scripts. The task was naming in Experiment 1 and semantic categorization in Experiment 2. The results showed that for Hangul words, there were significant word frequency effects in categorization, but not in naming, and that there were reliable script-switching effects in naming, but not in categorization. For Hanja words, however, there were clear and strong effects of words frequency, regardless of the task used, but significant effects of script-switching were only observed in categorization. These results suggest that the strategies adopted in processing Hangul and Hanja words are determined both by task demand and nature of the script.

Humans↗

PubMed1992

An automated indexing system utilizing semantic net expansion.

Automated subject indexing and the coordination of indexing with natural language search interfaces could provide solutions to some of the information retrieval problems facing the medical field today. This paper describes the construction of such an interface using semantic net expansion and a clinical neuroscience thesaurus, which provided a specialized vocabulary for use in both automated indexing of MEDLINE articles and an "intelligent" front-end for database searching. Though reviewed by a domain expert, the thesaurus was successfully built by nonexperts utilizing a set of rules. We report on testing thesaurus content and semantic net accuracy using a database of selected MEDLINE article abstracts.

Abstracting and Indexing↗