SEARCH · PubMed Health

Results for “Semantics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources

PubMed2004

An event-related brain potential study of sentence comprehension in preschoolers: semantic and morphosyntactic processing.

The goal of this study was to investigate the distinctiveness and the relative time course of the event-related brain potentials (ERP) elicited by syntactically and semantically anomalous words within sentences in 36- and 48-month-old children. ERPs were recorded while children listened to semantically anomalous (i.e., My uncle will blow the movie*), syntactically anomalous (i.e., My uncle will watching the movie*) and control sentences (i.e., My uncle will watch the movie). Semantic violations elicited a negative slow wave with different peaks at 400, 600 and 800 ms in both age groups, whereas the morphosyntactic violations elicited two positive shifts: the first starting at 200 ms with a frontal distribution over the scalp and the second starting at 600 ms and peaking around 800 ms with a broad distribution across the scalp in 36-month-olds and anteriorly distributed for 48-month-olds. These results show that preschoolers display different ERP patterns to syntactic and to semantic violations within sentences. It is possible that the ERP effects here reported are analogous to those elicited in adults by the same type of stimuli, although differences in topography are evident.

Acoustic Stimulation↗

PubMed2005

Musical structure modulates semantic priming in vocal music.

It has been shown that harmonic structure may influence the processing of phonemes whatever the extent of participants' musical expertise [Bigand, E., Tillmann, B., Poulin, B., D'Adamo, D. A., & Madurell, F. (2001). The effect of harmonic context on phoneme monitoring in vocal music. Cognition, 81, B11-B20]. The present study goes a step further by investigating how musical harmony may potentially interfere with the processing of words in vocal music. Eight-chord sung sentences were presented, their last word being either semantically related (La girafe a un tres grand cou, The giraffe has a very long neck) or unrelated to the previous linguistic context (La girafe a un tres grand pied, The giraffe has a very long foot). The target word was sung on a chord that acted either as a referential tonic chord or as a congruent but less referential subdominant chord. Participants performed a lexical decision task on the target word. A significant interaction was observed between semantic and harmonic relatedness suggesting that music modulates semantic priming in vocal music. Following Jones' dynamic attention theory, we argue that music can modulate semantic priming in vocal music, by modifying the allocation of attentional resource necessary for linguistic computation.

Humans↗

PubMed2005

Age of acquisition effects in picture naming: evidence for a lexical-semantic competition hypothesis.

In many tasks the effects of frequency and age of acquisition (AoA) on reaction latencies are similar in size. However, in picture naming the AoA-effect is often significantly larger than expected on the basis of the frequency-effect. Previous explanations of this frequency-independent AoA-effect have attributed it to the organisation of the semantic system or to the way phonological word forms are stored in the mental lexicon. Using a semantic blocking paradigm, we show that semantic context effects on naming latencies are more pronounced for late-acquired than for early-acquired words. This interaction between AoA and naming context is likely to arise during lexical-semantic encoding, which we put forward as the locus for the frequency-independent AoA-effect.

Age Factors↗

PubMed2005

The role of phonological activation in the visual semantic retrieval of Chinese characters.

The Stroop paradigm was used to examine the role of phonological activation in semantic access and its development in reading Chinese characters. Subjects (age 7-23 years) of different reading ability were asked to name the display color of Chinese characters. The characters were displayed in four different colors: red, yellow, blue and green. There were five types of relationships between a character and its display color: semantically congruent, phonologically congruent, semantically incongruent, phonologically incongruent and neutral. In addition to the classical Stroop effects, interference and facilitation effects from the homophones of color characters were also observed. The younger children and those with lower reading ability exhibited stronger Stroop effects. These findings suggest that phonological codes are activated automatically in Chinese character recognition. Furthermore, there is more phonological activation in the semantic retrieval of children in lower grades and those with lower reading ability.

Adult↗

PubMed2006

Cumulative semantic inhibition in picture naming: experimental and computational studies.

We report an experiment in which subjects named 120 pictures, consisting of series of five pictures drawn from each of 24 semantic categories (and intermixed with 45 fillers). The number of intervening trials (lag) between successive presentations of members of the same category varied from two to eight. Subjects' naming latencies were slowed by 30 ms for each preceding member of the category. This effect was both cumulative and linear, and unrelated to the lag elapsing since the previous presentation of a category member. These results definitively demonstrate the occurrence of cumulative interference for word retrieval by prior retrieval of other exemplars of the same semantic category-cumulative semantic inhibition. We claim that this inhibition effect could only occur if the spoken word production system possesses three specific properties (competition, priming, and sharing of semantic activation). We provide computational-modelling evidence in support of this claim. We show that no current theory of spoken word production has all of these properties. In their current form, all these theories are falsified by these results. We briefly discuss the obstacles that may be encountered by current models were they modified to account for our findings.

Adolescent↗

PubMed2005

Neural substrates of processing syntax and semantics in music.

Growing evidence indicates that syntax and semantics are basic aspects of music. After the onset of a chord, initial music-syntactic processing can be observed at about 150-400 ms and processing of musical semantics at about 300-500 ms. Processing of musical syntax activates inferior frontolateral cortex, ventrolateral premotor cortex and presumably the anterior part of the superior temporal gyrus. These brain structures have been implicated in sequencing of complex auditory information, identification of structural relationships, and serial prediction. Processing of musical semantics appears to activate posterior temporal regions. The processes and brain structures involved in the perception of syntax and semantics in music have considerable overlap with those involved in language perception, underlining intimate links between music and language in the human brain.

Acoustic Stimulation↗

PubMed2006

Nice wor_ if you can get the wor_: subliminal semantic and form priming in fragment completion.

Two experiments investigated subliminal semantic and form priming in a word-completion task. Visual gap-words with a dominant and a subordinate solution were preceded by form-related or by semantically related words, which were briefly presented and sandwich-masked. Priming of the subordinate solution was assessed in Experiment 1, relative to a neutral condition. Both solutions were primed in Experiment 2. In the absence of conscious prime recognition, both semantic and form primes reliably increased the probability with which the primed solution was given. With our variant of fragment-completion, response priming can be ruled out as explanation. Moreover, effects were already present at first presentation, excluding an interpretation in terms of partial awareness due to massive repetition. The data demonstrate automatic activation at both form and semantic levels in the absence of conscious awareness.

Adult↗

PubMed2006

Differential activation of frontal lobe areas by lexical and semantic language tasks: a functional magnetic resonance imaging study.

To determine whether frontal lobe regions, including Broca's area, dorsolateral prefrontal cortex (DLPFC) and supplementary motor area (SMA), are differentially activated during lexical and semantic language tasks, we used functional magnetic resonance imaging in eight healthy right-handed subjects silently performing two semantic tasks (adjective and verb generation) and a lexical retrieval task (noun recall). Activation was observed in Broca's area, DLPFC and SMA for all tasks. Broca's area activation was approximately doubled during the semantic tasks compared with the lexical task (verbs vs nouns: 19.1+/-4.5 vs 8.9+/-1.6 voxels, p=0.02; adjectives vs nouns 24.4+/-7.5 vs 10.1+/-2.8 voxels, p=0.04); however, there were no significant differences in the DLFPC or SMA across tasks. We conclude that Broca's area is more active during tasks that have a semantic content, whereas areas involved in preparatory processing (SMA) and memory retrieval (DLPFC) are engaged equally during both types of task.

Adult↗

PubMed2006

Semantic retrieval of spoken words with an obliterated initial phoneme in a sentence context.

Perception of a phoneme may occur even when the speech sound is missing (e.g., when an extraneous noise replaces the sound). This phenomenon, called phonemic restoration, has been observed to depend on the type of distortion. It requires a replacing sound that provides acoustic input to the auditory system, since the restoration has not been found when a speech sound was replaced by silence. We examined the brain activation underlying speech processing when the word's initial phoneme was completely replaced by a silent gap. Event-related potentials (ERPs) and reaction times (RTs) were measured as indicators of semantic processing of sentence final words. Slower voice onset times during repetition of the manipulated words as compared to normal words indicated increased difficulty in retrieving their meaning. The N400, which is related to the increased demands of the semantic integration of words, was elicited by less expected words as compared to highly expected ones. For manipulated words, the N400 was elicited at the same latency than for normal words, with respect to the onset of the remaining word fragment. The amplitude of the N400 was not increased, nor did it last longer, thereby indicating successful retrieval of the word's meaning based on the semantic context and remaining phonetic information. Thus, semantic retrieval does not seem to require the word's initial phoneme to be present in a sentence context. The results suggest that both context-driven expectancy (top-down) and stimulus-driven processes (bottom-up) are utilized in word processing and contribute to the overall N400 response.

Adult↗

PubMed2004

Influence of bodily harm on neural correlates of semantic and moral decision-making.

Moral decision-making is central to everyday social life because the evaluation of the actions of another agent or our own actions made with respect to the norms and values guides our behavior in a community. There is previous evidence that the presence of bodily harm--even if irrelevant for a decision--may affect the decision-making process. While recent neuroimaging studies found a common neural substrate of moral decision-making, the role of bodily harm has not been systematically studied so far. Here we used event-related functional magnetic resonance imaging (fMRI) to investigate how behavioral and neural correlates of semantic and moral decision-making processes are modulated by the presence of direct bodily harm or violence in the stimuli. Twelve participants made moral and semantic decisions about sentences describing actions of agents that either contained bodily harm or not and that could easily be judged as being good or bad or correct/incorrect, respectively. During moral and semantic decision-making, the presence of bodily harm resulted in faster response times (RT) and weaker activity in the temporal poles relative to trials devoid of bodily harm/violence, indicating a processing advantage and reduced processing depth for violence-related linguistic stimuli. Notably, there was no increase in activity in the amygdala and the posterior cingulate cortex (PCC) in response to trials containing bodily harm. These findings might be a correlate of limited generation of the semantic and emotional context in the anterior temporal poles during the evaluation of actions of another agent related to violence that is made with respect to the norms and values guiding our behavior in a community.

Adult↗

PubMed2004

Dissociating person-specific from general semantic knowledge: roles of the left and right temporal lobes.

The cognitive architecture and neural underpinnings of different semantic domains remains highly controversial. We report two patients with focal temporal lobe atrophy who presented with contrasting and theoretically informative dissociations of person-specific versus general semantic knowledge. Subject J.P. showed severely impaired person-specific semantics, with relative preservation of knowledge about objects and animals, while subject M.A. exhibited the opposite pattern of performance (good knowledge of people in the context of impoverished general semantics). Voxel-based morphometric analysis of MR images in the two cases established predominantly right temporal atrophy associated with J.P.'s deficit for person knowledge and predominantly left temporal atrophy in M.A. who was impaired in general conceptual knowledge.

Atrophy↗

PubMed2004

Remembering and forgetting of semantic knowledge in amnesia: a 16-year follow-up investigation of RFR.

We report our long-term follow-up investigations of RFR, a post-encephalitic case of very grave anterograde and retrograde amnesia. We also describe the results of quantitative neuroimaging of his brain injury that showed bilateral and severe reduction in the hippocampal formation and medial temporal structures with sparing of left lateral/posterior and right posterior temporal cortex. We established that RFR had a persistent severe anterograde and retrograde amnesia for personal and public events. His personal semantic knowledge was relatively spared for the retrograde period. There was a modest and global reduction in RFR's vocabulary for words acquired in adulthood before he became amnesic but there was no evidence of any retrograde gradient. His retrograde knowledge of people was also without any gradient. Remarkably, there had been no change in the extent of his semantic knowledge across a prolonged re-test interval indicating that the loss of semantic knowledge was stable and likely to have arisen at the time of his initial lesion. RFR also showed evidence of a limited but significant ability to acquire new word meanings and a more restricted capacity for learning about new celebrities. While he was able to demonstrate face and name familiarity for newly famous people, he was unable to provide much semantic detail. RFR's amnesia can be partially explained by contemporary theories that allow for parallel cortical and hippocampal memory systems but is difficult to reconcile in detail with any extant view.

Aged↗

PubMed2005

Episodic and semantic memory in mild cognitive impairment.

Little is known about episodic and semantic memory in the early predementia stage of Alzheimer's disease (AD), which is referred to as mild cognitive impairment (MCI). To explore person knowledge, item recognition and spatial associative memory, we designed the Face Place Test (FPT). A total of 75 subjects participated: 22 patients with early AD, 24 with MCI and 29 matched controls. As predicted, AD patients showed significant deficits in person naming, item recognition and recall of spatial location (placing). Surprisingly, subjects with MCI were also impaired on all components. There was no significant difference between AD and MCI except on the placing component. Analysis of the relationship between semantic (naming) and episodic (recognition and placing) components of the FPT revealed a significant association between the two episodic tasks, but not between episodic and semantic performance. Patients with MCI show deficits of episodic and semantic memory. The extent of impairment suggests dysfunction beyond the medial temporal lobe. The FPT might form the basis of a sensitive early indicator of AD.

Aged↗

PubMed2006

Knowing 7 x 8, but not the meaning of 'elephant': evidence for the dissociation between numerical and non-numerical semantic knowledge.

Patients affected by semantic dementia (SD) and other severe cognitive deficits may show preserved numerical skills, including the retrieval of multiplication facts from long-term memory. No studies so far specifically investigated the network of arithmetic facts in semantic dementia. Thus, it is unknown whether preserved multiplication in SD truly reflects intact semantic knowledge or preserved retrieval of verbal sequences (just as the recitation of rhymes or poems). In the present study a patient (SG) with SD underwent an extensive assessment of number processing and calculation abilities. In particular, multiplication knowledge was investigated through a series of computerised tasks (production task, multiple-choice task, number bisection task with multiplicative triplets, number-matching task). SG demonstrated excellent performance in all number processing and calculation tasks. In computerised tasks tapping multiplication fact knowledge, SG was as accurate and fast as healthy controls. Analyses on individual regression slopes indicated that SG's reaction time effects (problem-size effect, problem-difficulty effect, interference effects, and facilitation effect) were comparable to those found in controls in each task. These results add new evidence to the independence of numerical knowledge from other semantic information and provide further insight into the organisation of stored arithmetic knowledge.

Dementia↗

PubMed2006

Autobiographical memory in semantic dementia: implication for theories of limbic-neocortical interaction in remote memory.

We examined autobiographical memory performance in two patients with semantic dementia using a novel measure, the Autobiographical Interview [Levine, Svoboda, Hay, Winocur, & Moscovitch (2002). Aging and autobiographical memory: Dissociating episodic from semantic retrieval. Psychology and Aging, 17, 677-689], that is capable of dissociating episodic and personal semantic recall under varying levels of retrieval support. Earlier reports indicated that patients with semantic dementia demonstrate autobiographical episodic memory loss following a "reverse gradient" by which recent memories are preserved relative to remote memories. We found limited evidence for this pattern at conditions of low retrieval support. When structured probing was provided, patients' autobiographical memory performance was similar to that of controls. Retesting of one patient after 1 year indicated that retrieval support was insufficient to bolster performance following progressive prefrontal volume loss, as documented with quantified structural neuroimaging. These findings are discussed in relation to theories of limbic-neocortical interaction in autobiographical memory.

Adolescent↗

PubMed2006

Semantic and phonological task-set priming and stimulus processing investigated using magnetoencephalography (MEG).

In this study the neural substrates of semantic and phonological task priming and task performance were investigated using single word task-primes. Magnetoencephalography (MEG) data were analysed using Synthetic Aperture Magnetometry (SAM) to determine the spatiotemporal and spectral characteristics of cortical responses. Comparisons were made between the task-prime conditions for evidence of differential effects as a function of the nature of the task being primed, and between the task-prime and the task performance responses for evidence of parallels in activation associated with preparation for and completion of a specific task. Differential priming effects were found. Left middle temporal and inferior frontal voxels showed a statistically significant power decrease associated with the semantic task-prime, and a power increase associated with the phonological task-prime, within beta and gamma frequency bands respectively. Similarities between the task-related differential effects associated with task-prime presentation and those associated with target stimulus presentation were also found. For example, within the semantic task condition, left superior frontal and middle temporal regions showed a significant power decrease within both task-prime and target epochs; within the phonological task condition there were significant parietal and cerebellar power decreases within both types of epoch. In addition there was evidence within the priming epochs of dissociable patterns of activity which could be interpreted as indices of de-activation of task-irrelevant networks. Following a phonological task-prime, significant power increases were observed in those inferior frontal and middle temporal regions in which significant power decreases were associated with semantic task priming and performance.

Brain Mapping↗

PubMed2004

Affective semantic priming in patients with schizophrenia.

Affective semantic priming was examined in normal controls and patients with schizophrenia using a lexical decision task with four affective categories of related word pairs: neutral, happy, fearful and sad. Results demonstrated a striking and reliable effect of affective category upon semantic priming. Neutral and happy prime targets yielded significant semantic priming. Fearful and sad pairs showed no or modest semantic priming facilitation. Schizophrenia patients did not differ from normal controls on their priming scores to any of the four affective categories. These results support the notion that the associative mechanisms that bind negative valence words are distinct in nature; they also clarify that patients with schizophrenia do not show increased sensitivity to affect, and more specifically negative affective context during priming paradigms. This study further indicates the importance of replicating novel findings and reporting negative results.

Adolescent↗

PubMed2004

Semantic fluency is impaired but phonemic and design fluency are preserved in early-onset schizophrenia.

Impairments of verbal fluency are recognised in adult-onset schizophrenia but their presence in early-onset schizophrenia is not well established. This study investigated the extent and character of verbal fluency disturbance in young patients close to illness onset. Thirty-three adolescents with DSM-IV schizophrenia and 33 controls completed phonemic and semantic fluency tests and a free design fluency test. Patients had significantly impaired semantic fluency compared to controls but no impairment on phonemic or design fluency. The difference between patients and controls for semantic fluency remained significant when corrected for age and IQ. These results lend support to the hypothesis that impaired semantic fluency may be an early trait marker of schizophrenia that is potentially related to a failure of lateralisation of language.

Adolescent↗