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PubMed2005

Lexical priming and semantic integration reflected in the event-related potential of 14-month-olds.

This study investigates by means of the event-related brain potential whether mechanisms of lexical priming and semantic integration are already developed in 14-month-olds. While looking at coloured pictures of known objects children were presented with basic-level words that were either congruous or incongruous to the pictures. The event-related potential of 14-month-olds revealed an early negativity in the lateral frontal brain region for congruous words, and a later N400-like negativity for incongruous words. These results indicate that both lexical priming and semantic integration are already present as early as 14 months.

Acoustic Stimulation↗

PubMedDate not supplied

Brain correlates of performance in a free/cued recall task with semantic encoding in Alzheimer disease.

The goal of this study was to explore in patients with Alzheimer's disease (AD) the brain correlates of free and cued recall performance using an adaptation of the procedure developed by Grober and Buschke (1987). This procedure, which ensures semantic processing and coordinates encoding and retrieval, has been shown to be very sensitive to an early diagnosis of AD. Statistical parametric mapping (SPM 99) was used to establish clinicometabolic correlations between performance at free and cued verbal recall and resting brain metabolism in 31 patients with AD. Results showed that patient's score on free recall correlated with metabolic activity in right frontal regions (BA 10 and BA 45), suggesting that performance reflected a strategic retrieval attempt. Poor retrieval performance was tentatively attributed to a loss of functional correlation between frontal and medial temporal regions in patients with AD compared with elderly controls. Performance on cued recall was correlated to residual metabolic activity in bilateral parahippocampal regions (BA 36), suggesting that performance reflected retrieval of semantic associations, without recollection in AD. In conclusion, this study demonstrates that the diagnostic sensitivity for Alzheimer's disease of the cued recall performance in the Grober and Buschke procedure (1987) depends on the activity of parahippocampal regions, one of the earliest targets of the disease. Moreover, the results suggest that the poor performance of patients with AD during free and cued recall is related to a decreased connectivity between parahippocampal regions and frontal areas.

Aged↗

PubMed2006

Lexical-semantic processes in children with specific language impairment.

The current study used event-related brain potentials to investigate lexical-semantic processing of words in sentences spoken by children with specific language impairment and children with normal language development. Children heard correct sentences and sentences with a violation of the selectional restriction of the verb. Control children showed an N400 effect followed by a late positivity for the incorrect sentences. In contrast, children with specific language impairment showed no N400 effect but did show a late, broadly distributed positivity. This absence of the N400 effect is due to a relatively large negativity for correct sentences, suggesting weaker lexical-semantic representations of the verbs and their selectional restrictions in children with specific language impairment.

Acoustic Stimulation↗

PubMed2003

Abstraction and natural language semantics.

According to the traditional view, a word prototypically denotes a class of objects sharing similar features, i.e. it results from an abstraction based on the detection of common properties in perceived entities. I explore here another idea: words result from abstraction of common premises in the rules governing our actions. I first argue that taking 'inference', instead of 'reference', as the basic issue in semantics does matter. I then discuss two phenomena that are, in my opinion, particularly difficult to analyse within the scope of traditional semantic theories: systematic polysemy and plurals. I conclude by a discussion of my approach, and by a summary of its main features.

Concept Formation↗

PubMed2005

Semantics-based information modeling for the health-care administration sector: the citation platform.

An information brokerage environment for effective information structuring, indexing, and retrieval in the health-care administration sector is presented. The system is based on ontology modeling, natural language processing, extensible markup language, semantics analysis, and behavioral description. Semantics-based information acquisition is achieved through the uniform modeling, representation, and handling of domain-specific knowledge, both content-based and procedural. The system has been validated using information located on several repositories in the web and its performance is reported in terms of precision and recall.

Artificial Intelligence↗

PubMedDate not supplied

Visual analysis of large heterogeneous social networks by semantic and structural abstraction.

Social network analysis is an active area of study beyond sociology. It uncovers the invisible relationships between actors in a network and provides understanding of social processes and behaviors. It has become an important technique in a variety of application areas such as the Web, organizational studies, and homeland security. This paper presents a visual analytics tool, OntoVis, for understanding large, heterogeneous social networks, in which nodes and links could represent different concepts and relations, respectively. These concepts and relations are related through an ontology (also known as a schema). OntoVis is named such because it uses information in the ontology associated with a social network to semantically prune a large, heterogeneous network. In addition to semantic abstraction, OntoVis also allows users to do structural abstraction and importance filtering to make large networks manageable and to facilitate analytic reasoning. All these unique capabilities of OntoVis are illustrated with several case studies.

Algorithms↗

PubMed2003

Semantic categorization in the human brain: spatiotemporal dynamics revealed by magnetoencephalography.

We examined the cortical representation of semantic categorization using magnetic source imaging in a task that revealed both dissociations among superordinate categories and associations among different base-level concepts within these categories. Around 200 ms after stimulus onset, the spatiotemporal correlation of brain activity elicited by base-level concepts was greater within than across superordinate categories in the right temporal lobe. Unsupervised clustering of data showed similar categorization between 210 and 450 ms mainly in the left hemisphere. This pattern suggests that well-defined semantic categories are represented in spatially distinct, macroscopically separable neural networks, independent of physical stimulus properties. In contrast, a broader, task-required categorization (natural/man-made) was not evident in our data. The perceptual dynamics of the categorization process is initially evident in the extrastriate areas of the right hemisphere; this activation is followed by higher-level activity along the ventral processing stream, implicating primarily the left temporal lobe.

Adult↗

PubMed2005

Semantic memory retrieval: cortical couplings in object recognition in the N400 window.

To characterize the regional changes in neuronal couplings and information transfer related to semantic aspects of object recognition in humans we used partial-directed EEG-coherence analysis (PDC). We examined the differences of processing recognizable and unrecognizable pictures as reflected by changes in cortical networks within the time-window of a determined event-related potential (ERP) component, namely the N400. Fourteen participants performed an image recognition task, while sequentially confronted with pictures of recognizable and unrecognizable objects. The time-window of N400 as indicative of object semantics was defined from the ERP. Differences of PDC in the beta-band between these tasks were represented topographically as patterns of electrical couplings, possibly indicating changing degrees of functional cooperation between brain areas. Successful memory retrieval of picture meaning appears to be supported by networks comprising left temporal and parietal regions and bilateral frontal brain areas.

Adult↗

PubMed2004

Training 2;6-year-olds to produce the transitive construction: the role of frequency, semantic similarity and shared syntactic distribution.

Childers and Tomasello (2001) found that training 2 1/2-year-olds on the English transitive construction greatly improves their performance on a post-test in which they must use novel verbs in that construction. In the current study, we replicated Childers and Tomasello's finding, but using a much lower frequency of transitive verbs and models in training. We also used novel verbs that were of a different semantic class to our training verbs, demonstrating that semantic homogeneity is not crucial for generalization. We also replicated the finding that 4-year-olds are significantly more productive than 2 1/2-year-olds with the transitive construction, with the new finding that this is also true for verbs of emission. In addition, 'shared syntactic distribution' of novel verb and training verbs was found to have no observable effect on the number of 2 1/2-year-olds who were productive in the post-test.

Child, Preschool↗

PubMed2005

Factors responsible for performance on the day-night task: response set or semantics?

In a recent study Diamond, Kirkham and Amso (2002) obtained evidence consistent with the claim that the day-night task requires inhibition because the picture and its corresponding conflicting response are semantically related. In their study children responded more accurately in a dog-pig condition (see /day picture/ say "dog"; see /night picture/ say "pig") than the standard day-night condition (see /day picture/ say "night"; see /night picture/ say "day"). However, there is another effect that may have made the day-night condition harder than the dog-pig condition: the response set effect. In the day-night condition the names of the two stimuli ("day" and "night") and the two corresponding conflicting responses ("night" and "day") are from the same response set: both "day" and "night". In the dog-pig condition the names of the stimuli ("day", "night") and the corresponding responses ("dog", "pig") are from a different response set. In two experiments (Experiment 1 with 4-year-olds (n = 25); Experiment 2 with , 4-, 5-, 7- and 11-year-olds (n = 81)) children were tested on four experimental conditions that enabled the effects of semantics and response set to be separated. Overall, our data suggest that response set is a major factor in creating the inhibitory demands of the day-night task in children of all ages. Results are discussed in relation to other inhibitory tasks.

Age Factors↗

PubMed1992

Event related potentials and EEG components in a semantic memory search task.

This study examined the effects of memory search and related processes on both time and frequency domain components of electroencephalographic activity. More specifically, we were interested in the relationship between EEG and event-related potential (ERP) components as a function of memory load and response type. Subjects performed a semantic memory search task in which they matched word probes to category labels. Consistent with previous studies, reaction time increased and accuracy decreased with increasing memory loads. A negative component of the ERP (N400) was found to reflect semantic mismatch: N400s were larger for the nontargets than for the targets. Two ERP components were found to be reciprocally related to memory load. P300 decreased and Negative Slow Wave increased in amplitude with increases in the size of the memory set. These two ERP components were reflected by different components in a Principal Components Analysis. The power in the theta band (5-7 Hz) also increased as a function of memory load and appears to be functionally and topographically related to the Negative Slow Wave in the ERP. It is argued that both measures are jointly determined and reflect the difficulty of the conceptual operations during memory search.

Adult↗

PubMed1993

An event-related potential study of semantic congruity and repetition in a sentence-reading task: effects of context change.

This experiment examined the joint effects of semantic congruity and repetition on event-related brain potentials (ERPs) elicited in a sentence priming task. In an initial training phase, subjects were familiarized with a list of 60 congruous and incongruous sentences. During the second phase, ERPs were recorded as subjects silently read a set of 180 unconnected sentences. One third of the sentences were presented exactly as they had been seen in training (Old sentences), one third were presented for the first time (Completely New sentences), and one third involved a re-pairing of the frames and completions of the congruous and incongruous Old sentences (New Pair sentences). The N400 congruity effect was reduced for Old as compared with Completely New and New Pair sentence completions. These results suggest that N400 reflects processes that are sensitive to both existing semantic associations and representations of previous episodes that include the context of the eliciting stimulus. A late positive component (LPC) involving a sustained positive shift in the waveform after 600 ms was largest for incongruous completions and occurred somewhat earlier for Old sentences. This pattern of results is consistent with the notion that the LPC is an index of episodic retrieval and elaborative processes. The data also suggest the presence of an early onset slow positive shift that is only evident for New Pair congruous sentences.

Adolescent↗

PubMed1996

Is an apple a fruit? Semantic relatedness as reflected by psychophysiological responsivity.

In the present study, we investigated orienting response generalization across various types of semantically related stimuli. Four experiments, based on a modified version of the guilty knowledge technique, were designed to examine whether semantic relations based on abstract features are reflected by electrodermal responsivity. No generalization across coordinates was obtained, but a moderate degree of generalization was demonstrated between a word and its superordinate category (e.g., table-furniture) and between a word and its synonym. Complete generalization occurred from a verbal label of an object to its pictorial representation, and vice versa. These results are compatible with our proposal that partial identification of the test stimulus as relevant is a necessary condition for generalization in the guilty knowledge technique.

Adult↗

PubMed2004

ERP indices of emotionality and semantic cohesiveness during recognition judgments.

Event-related potentials (ERPs) were used to examine the impact of emotionality on false recognition. In Experiment 1, participants discriminated previously studied words from neutral and negatively valenced emotional foils. Emotional words elicited a more positive ERP than did neutral words and emotional foils were falsely recognized more often than neutral foils. In Experiment 2, the hypothesis that emotionality-based false recognition is due to the semantic cohesiveness of emotional words was tested by including a highly associated but emotionally neutral category (animals). It was emotional and not animal foils that elicited greater positivity in the ERP and increased false positive response. These data provide little support for semantic cohesiveness as the basis for false recognition effects, but are consistent with the view that the salience of emotional words can be falsely attributed to familiarity in the context of a recognition task.

Adult↗

PubMed1993

Acute exercise facilitates semantically cued memory in nursing home residents.

OBJECTIVE: To study the acute effects of non-strenuous physical exercise on memory retrieval and visuo-motor performance in old-old nursing home residents. DESIGN: A randomized control trial. SETTING: A nursing home. PARTICIPANTS: Ambulatory volunteers from the nursing home, with all 20 shown to be normal on mental status. Three were male and 17 female, with a means of 84.5 years for age and 9.3 years for education. They were divided at random into an exercise and a control group. INTERVENTION: A single 15-minute standardized bout of non-strenuous exercise administered independently to each participant in the exercise group. Control group participants watched a video of similar exercises for 15 minutes. MEASUREMENTS: Two measures requiring the retrieval of category instances with semantic or initial consonant cues. Retrieval time was 60 seconds for each of four categories per measure. Visuo-motor performance was measured by Symbol Digit coding. Testing sessions were held before exercise, immediately post-exercise and 30 minutes post-exercise. RESULTS: The group-by-time interaction was significant only for semantically cued memory (P < 0.01), with higher retrieval at post-testing only in the exercised group. The higher retrieval was mainly attributable to more new items retrieved by the exercise group at the immediate post-test (P < 0.05). CONCLUSIONS: This study provides preliminary support for the hypothesis that non-strenuous physical exercise has positive acute effects on meaningfully cued memory.

Aged↗

PubMed2000

The scientific origin of life. Considerations on the evolution of information, leading to an alternative proposal for explaining the origin of the cell, a semantically closed system.

We hypothesize that the origin of life, that is, the origin of the first cell, cannot be explained by natural selection among self-replicating molecules, as is done by the RNA-world hypothesis. To circumvent the chicken and egg problem associated with semantic closure of the cell--no replication of information molecules (nucleotide strands) without functional enzymes, no functional enzymes without encoding in information molecules--a prebiotic evolutionary process is proposed that, from the informational point of view, must somehow have resembled the current scientific process. The cell was the outcome of interactions of a complex premetabolic community, with information molecules that were devoid of self-replicative properties. In a comparable manner, scientific progress is possible, essentially because of interaction between a complex cultural society and permanent information carriers like printed matter. This may eventually lead to self-replicating technology in which semantic closure occurs anew. Explaining the origin of life as a scientific process might provide a unifying theory for the evolution of information, wherebye at two moments symbolization/encoding of interactions into permanent information occurred: at one moment that of chemical interaction and at another moment that of animal behavior interaction. In one event this encoding led to autonomously duplicating chemistry (the cell), an event that possibly may be one of the outcomes of current scientific progress.

Origin of Life↗

PubMed1989

Retrieval from semantic memory using meaningful and meaningless constructs by depressed, stable bipolar and manic patients.

Eleven depressed, 11 stable bipolar and six manic patients, 20 normals and eight late middle-age normals were tested for speech production using a word-fluency task. Fluency was prompted by either a letter (a relatively automatic task), or a semantic category (an effort-demanding task). The results showed that depressed patients were more impaired in speech production than other patients when prompted by a semantic category than when prompted by a letter. A post hoc matched-tasks check suggested that this finding was not due to differences in discriminating power between the two word-fluency tasks. Manic and stable bipolar patients did not differ in their speech production, although matched on age. The results suggest that depressives perform better on more automatic than on effort-demanding tasks, and that manic and stable bipolar patients do not differ in speech production when experimentally imposed restrictions are present.

Adult↗

PubMed2003

The relationship between acoustic structure and semantic information in Diana monkey alarm vocalization.

Mammalian vocal production mechanisms are still poorly understood despite their significance for theories of human speech evolution. Particularly, it is still unclear to what degree mammals are capable of actively controlling vocal-tract filtering, a defining feature of human speech production. To address this issue, a detailed acoustic analysis on the alarm vocalization of free-ranging Diana monkeys was conducted. These vocalizations are especially interesting because they convey semantic information about two of the monkeys' natural predators, the leopard and the crowned eagle. Here, vocal tract and sound source parameter in Diana monkey alarm vocalizations are described. It is found that a vocalization-initial formant downward transition distinguishes most reliably between eagle and leopard alarm vocalization. This finding is discussed as an indication of articulation and alternatively as the result of a strong nasalization effect. It is suggested that the formant modulation is the result of active vocal filtering used by the monkeys to encode semantic information, an ability previously thought to be restricted to human speech.

Acoustics↗