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PubMed1999

Mapping of semantic, phonological, and orthographic verbal working memory in normal adults with functional magnetic resonance imaging.

Twelve neurologically normal participants (4 men and 8 women) performed semantic, phonological, and orthographic working memory tasks and a control task during functional magnetic resonance imaging. Divergent regions of the posterior left hemisphere used for decoding and storage of information emerged in each working memory versus control task comparison. These regions were consistent with previous literature on processing mechanisms for semantic, phonological, and orthographic information. Further, working memory versus control task differences extended into the left frontal lobe, including premotor cortex, and even into subcortical structures. Findings were consistent with R. C. Martin and C. Romani's (1994) contention that different forms of verbal working memory exist and further suggest that a reconceptualization of premotor cortex functions is needed.

Adolescent↗

PubMed2000

Processing lexical ambiguities in word triplets: evidence of lexical-semantic deficits following dominant nonthalamic subcortical lesions.

Lexical-semantic function was investigated in 10 participants with lesions of the dominant nonthalamic subcortical (NS) region and a matched normal control group. Participants performed speeded lexical decisions on the 3rd member of auditorily presented word triplets. The 4 critical triplet conditions were concordant (coin-bank-money), discordant (river-bank-money), neutral (day-bank-money), and unrelated (river-day-money). When the interstimulus interval (ISI) between the words in the triplets was 100 ms, patients with NS lesions obtained priming that indicated nonselective lexical access; at 1,250-ms ISI, however, there was no significant priming effect. This pattern of results is consistent with the view that patients with NS lesions can automatically access lexical-semantic information but may be unable to sustain lexical activation through controlled or attentional forms of processing.

Aged↗

PubMed2003

Long-term semantic memory versus contextual memory in unconscious number processing.

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 as larger than 55, the novel masked prime 37 paradoxically facilitated the "larger" response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory.

Attention↗

PubMed2003

ERP evidence for the time course of graphic, phonological, and semantic information in Chinese meaning and pronunciation decisions.

Two words that varied in their relationship were presented sequentially to Chinese readers who made meaning and pronunciation decisions. In the meaning task, they decided whether the words had the same meaning. In the pronunciation task, they decided whether the words had the same pronunciation. In both tasks, the word pairs represented 1 of 4 relationships: graphically similar, homophonic, semantically related, or unrelated. Event related potentials (ERP) recordings made from the onset of the 2nd word suggested a temporal unfolding of graphic, phonological, and semantic effects. Specifically, graphically-related pairs produced a smaller P200 in the pronunciation task and a smaller N400 in the meaning task. Homophones produced reduced N400 component with bilateral sources in the meaning task.

Adult↗

PubMed2003

In search of perceptual priming in a semantic classification task.

Four experiments tested for perceptual priming for written words in a semantic categorization task. Repetition priming was obtained for low-frequency words when unrelated categorizations were performed at study and test (Experiment 1), but it was not orthographically mediated given that written-to-written and spoken-to-written word priming was equivalent (Experiments 2 and 3). Furthermore, no priming was obtained between pictures and words (Experiment 4), suggesting that the nonorthographic priming was largely phonological rather than semantic. These results pose a challenge to standard perceptual theories of priming that should expect orthographic priming when words are presented in a visual format at study and test.

Adult↗

PubMed1998

Imaging unconscious semantic priming.

Visual words that are masked and presented so briefly that they cannot be seen may nevertheless facilitate the subsequent processing of related words, a phenomenon called masked priming. It has been debated whether masked primes can activate cognitive processes without gaining access to consciousness. Here we use a combination of behavioural and brain-imaging techniques to estimate the depth of processing of masked numerical primes. Our results indicate that masked stimuli have a measurable influence on electrical and haemodynamic measures of brain activity. When subjects engage in an overt semantic comparison task with a clearly visible target numeral, measures of covert motor activity indicate that they also unconsciously apply the task instructions to an unseen masked numeral. A stream of perceptual, semantic and motor processes can therefore occur without awareness.

Adult↗

PubMed2002

VANQUIS, a system for the interactive semantic content analysis and spatio-temporal query by content of videos.

Using the video metadata descriptors and data model defined in the accompanying paper (Shotton, D. M. et al. (2002) A metadata classification schema for semantic content analysis of videos. J. Microsc. 205, 33-42), we discuss how analysis of the content of scientific videos, and subsequent query by content of the resulting semantic metadata, can be enhanced by the use of an object-relational database. We illustrate this by describing VANQUIS, a Web-based prototype video analysis and query interface system for the interactive spatio-temporal analysis and subsequent query by content of videos. Using VANQUIS to generate standard SQL (structured query language) statements that address complex data types stored in an object-relational database, relationships between characters and events contained within and between videos can be identified, and the appropriate video segments containing these characters and events can be retrieved for viewing. We give examples of analysis and query implementation by using VANQUIS to analyse a biological microscopy video, and discuss the wider potential of this methodology for the analysis and query by content of videos containing more general subject matter.

Comment↗

PubMed1999

Perceptual and linguistic interactions in speeded classification: tests of the semantic coding hypothesis.

We tested the semantic coding hypothesis, which states that cross-modal interactions observed in speeded classification tasks arise after perceptual information is recoded into an abstract format common to perceptual and linguistic systems. Using a speeded classification task, we first confirmed the presence of congruence interactions between auditory pitch and visual lightness and observed Garner-type interference with nonlinguistic (perceptual) stimuli (low-frequency and high-frequency tones, black and white squares). Subsequently, we found that modifying the visual stimuli by (a) making them lexical (related words) or (b) reducing their compactness or figural 'goodness' altered congruence effects and Garner interference. The results are consistent with the semantic coding hypothesis, but only in part, and suggest the need for additional assumptions regarding the role of perceptual organization in cross-modal dimensional interactions.

Female↗

PubMed2003

Real-time semantic compensation in patients with agrammatic comprehension: electrophysiological evidence for multiple-route plasticity.

To understand spoken language requires that the brain provides rapid access to different kinds of knowledge, including the sounds and meanings of words, and syntax. Syntax specifies constraints on combining words in a grammatically well formed manner. Agrammatic patients are deficient in their ability to use these constraints, due to a lesion in the perisylvian area of the language-dominant hemisphere. We report a study on real-time auditory sentence processing in agrammatic comprehenders, examining their ability to accommodate damage to the language system. We recorded event-related brain potentials (ERPs) in agrammatic comprehenders, nonagrammatic aphasics, and age-matched controls. When listening to sentences with grammatical violations, the agrammatic aphasics did not show the same syntax-related ERP effect as the two other subject groups. Instead, the waveforms of the agrammatic aphasics were dominated by a meaning-related ERP effect, presumably reflecting their attempts to achieve understanding by the use of semantic constraints. These data demonstrate that although agrammatic aphasics are impaired in their ability to exploit syntactic information in real time, they can reduce the consequences of a syntactic deficit by exploiting a semantic route. They thus provide evidence for the compensation of a syntactic deficit by a stronger reliance on another route in mapping sound onto meaning. This is a form of plasticity that we refer to as multiple-route plasticity.

Adult↗

PubMed2002

Interactions between thalamic and cortical rhythms during semantic memory recall in human.

Human scalp electroencephalographic rhythms, indicative of cortical population synchrony, have long been posited to reflect cognitive processing. Although numerous studies employing simultaneous thalamic and cortical electrode recording in nonhuman animals have explored the role of the thalamus in the modulation of cortical rhythms, direct evidence for thalamocortical modulation in human has not, to our knowledge, been obtained. We simultaneously recorded from thalamic and scalp electrodes in one human during performance of a cognitive task and found a spatially widespread, phase-locked, low-frequency rhythm (7-8 Hz) power decrease at thalamus and scalp during semantic memory recall. This low-frequency rhythm power decrease was followed by a spatially specific, phase-locked, fast-rhythm (21-34 Hz) power increase at thalamus and occipital scalp. Such a pattern of thalamocortical activity reflects a plausible neural mechanism underlying semantic memory recall that may underlie other cognitive processes as well.

Brain Mapping↗

PubMed1989

The autobiographical memory interview: a new assessment of autobiographical and personal semantic memory in amnesic patients.

This paper describes a new technique for assessing "autobiographical" and "personal semantic" memory in amnesic patients and healthy controls. It provides evidence of the reliability and validity of the procedure, and reports an age-related temporal gradient in amnesic patients. The results are considered in terms of the severity, the rate of onset, and the duration of the amnesia; and a preliminary analysis is given of the findings in different diagnostic groups. The findings indicate that autobiographical and personal semantic memory show a consistent pattern of impairment, when a comparison is made which controls for the age of the memories and the subject's own past experience.

Adult↗

PubMedDate not supplied

The semantics of addiction: moving beyond expert models to lay understandings.

Five expert discourses on addiction purport to explain the phenomenon of the semantics of addiction. An assessment of the burgeoning use of this term by the lay public, however, reveals a plethora of socially contextualized and culturally mediated meanings related to addiction that are generally not considered by expert models. Addiction has meanings that index the loss of self-control and individual responsibility, as well political and moral meanings and meanings that index social modes of consumption, the range and limits of normative behavior, and the constitution of deviance. The category of addition interacts with other socially produced categories, including "drugs" and "desires," and implies an unfolding history linked to specific cultural conventions of what is proper. This paper briefly reviews expert debates over the meanings of addiction and explores the semantics of how this term is used in both popular discourse and among those who use substances associated with physical addiction. In addition, some of the more interesting theoretical issues this discussion brings to light are highlighted, with the intent to identify issues warranting future research that will broaden the study of addiction.

Humans↗

PubMed2005

Can episodic memory tasks differentiate semantic dementia from Alzheimer's disease?

The performance of two groups of patients with semantic dementia (SD), with predominant right (SDR) and left temporal lobe atrophy (SDL), was contrasted with that of cases with probable Alzheimer's disease (AD) on a range of standard episodic memory tasks. While the SDL group achieved a good score on a composite visual, but not a verbal, episodic memory measure, the AD and SDR groups were equivalently impaired at visual and verbal memory. The SD, but not the AD, groups were, by definition, impaired on simple tests of semantic memory. Standard verbal episodic memory tests, therefore, failed to discriminate patients with SD from those with probable AD and even visual memory tests may result in misclassification of SDR cases.

Aged↗

PubMedDate not supplied

A semantic-based kernel for advanced health information systems.

This paper reports on the design and development of an infrastructure allowing one to share and exchange multimedia data in the context of a health network. A single technology exploiting a semantic model of the hospital universe provides users with information and data of diverse origins, generated by the various actors or departments of the health organization. Functions provided include act management and patient record management governed by domain semantics. The functionality has been validated through laboratory experiments against the requirements of protocol directed care and health networks. The functionality is integrated into a clinician workstation exploited in the Internet/Intranet environment thanks to a commercial browser. These results have been obtained with the support of several projects in the frame of the Health-Care Telematics Applications Programme of the European Community and of the Eurêka Programme.

Artificial Intelligence↗

PubMed1996

Response biases in oral reading: an account of the co-occurrence of surface dyslexia and semantic dementia.

This paper reports a case study of a subject (EP) with a progressive impairment of semantic memory and a coincident surface dyslexia. These two disorders frequently occur together, but their association is not readily explained within current models of reading. This study investigated two theories that offer different principled accounts of this association, the "semantic glue hypothesis" (Patterson & Hodges, 1992) and the "summation hypothesis" (Hillis & Caramazza, 1991) and found both hypotheses wanting. Instead it was shown that when vestiges of word meaning remained, a lexical response was preferred, but when meaning was lost entirely, the evidence derived from sublexical processing appeared to bias selection of the response towards the regularized form.

Atrophy↗

PubMed1986

Memory for scenes in stroke patients. Hemisphere processing of semantic organization in pictures.

Twenty-one patients with cerebrovascular lesions in posterior regions of the left or right cerebral hemispheres and nonfluent aphasics with damage in anterior regions of the left hemisphere were administered a specially designed multiple-object pictorial test which measured long-term memory for scenes depicting real world schemata versus jumbled unorganized scenes. The units in the pictures were familiar figures. Memory was tested separately for single details and for whole scenes. The results showed that within the left posterior group there was significantly poorer memory for unorganized relative to organized stimuli, especially for whole scenes. There was also a selective dissociation between the left and right posterior patients on the detail versus whole scene probes in the unorganized stimuli. At the same time, organized scenes depicting real world schemata were not selectively impaired in any of the patient groups. Further, the overall memory scores on the Memory for Pictorial Scenes Test obtained by the aphasic patients were not significantly lower than those obtained by the control subjects, while scores of both posterior groups were lower than the control group. Taken together, the data suggest the following. Pictorial semantics, like linguistic semantics, are functions processed by the left posterior cortex. While the posterior region in the left hemisphere plays a special role in remembering visual situational schemata that are newly encountered, familiar visual situational schemata may be bilaterally represented.

Cerebral Cortex↗

PubMed2003

Conversion of semantic information into phonological representation: a function in left posterior basal temporal area.

A unique feature of Japanese language is that its written sentences consist of both morphograms (kanji) and syllabograms (kana). Despite extensive research by PET, functional MRI and magnetoencephalography, the issues of the difference (or the similarities) between the processing of kanji and kana, and between word reading and object/picture naming have not been resolved as yet. This study investigated the function of the posterior basal temporal area in the language dominant hemisphere in auditory and visual language processing, with special emphasis on semantic and phonological recognition. Subdural electrode grids were placed on the left temporal area of a right-handed woman with intractable temporal lobe epilepsy as part of a pre-surgical evaluation. Her dominant hemisphere for language was shown to be the left on the Wada test. Electric stimulation of 50 Hz was applied to the electrodes during the tasks related to language. Our results showed a clear distinction in the responses and/or performance of the subject depending on the type of characters presented and the tasks employed. Electric stimulation of a localized area in the posterior basal temporal lobe caused neither comprehensive nor productive deficit in the tasks using auditory stimuli. In the tasks using visual stimuli, in contrast, impairments were observed in (i) reading of kanji words and (ii) naming of objects/pictures and geometric designs, but not in (iii) reading of kana, (iv) copying of kanji, kana and geometric designs, and (v) using tools. The subject maintained full comprehension of spoken language, suggesting that the auditory tasks are not processed in the posterior basal temporal area. The fact that the impairment of kanji reading and disturbance of object/picture naming were elicited by electric stimulation of the same area indicates that there is at least one anatomical area that is used commonly for kanji (but not kana) and object processing. The conceptual entity of the test items supposedly was recognized correctly, but the concept failed to be matched to correct phonological representation. The left posterior basal temporal area, therefore, has an important function of connecting visual semantic information into phonological representation.

Adult↗

PubMed1997

Semantic factors in episodic recognition of common odors in early and late adulthood: a review.

Information on long-term memory for common odors is discussed. Olfactory parameters (i.e. familiarity, recognition, identification) and their relationship to current memory theory are highlighted. Emphasis is focused on the impact of semantic memory on episodic odor recognition. In contrast to previous research suggesting that verbal/semantic factors play a negligible role in olfactory memory, the present review indicates that episodic odor information is mediated by factors that can be subsumed under the rubric of semantic memory. Specific odor knowledge, such as perceived familiarity and identifiability, is strongly and positively related to episodic odor memory performance. Age-related impairments in various olfactory and cognitive parameters and the potential detrimental effects in episodic odor memory are discussed. Finally, the issue of whether olfactory memory should be conceptualized as an independent process, or whether it shares characteristics with memory for verbal and visual information, is addressed.

Adult↗

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