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PubMed2005

Automatic priming of semantically related words reduces activity in the fusiform gyrus.

We used rapid, event-related fMRI to identify the neural systems underlying object semantics. During scanning, subjects silently read rapidly presented word pairs (150 msec, SOA = 250 msec) that were either unrelated in meaning (ankle-carrot), semantically related (fork-cup), or identical (crow-crow). Activity in the left posterior region of the fusiform gyrus and left inferior frontal cortex was modulated by word-pair relationship. Semantically related pairs yielded less activity than unrelated pairs, but greater activity than identical pairs, mirroring the pattern of behavioral facilitation as measured by word reading times. These findings provide strong support for the involvement of these areas in the automatic processing of object meaning. In addition, words referring to animate objects produced greater activity in the lateral region of the fusiform gyri, right superior temporal sulcus, and medial region of the occipital lobe relative to manmade, manipulable objects, whereas words referring to manmade, manipulable objects produced greater activity in the left ventral premotor, left anterior cingulate, and bilateral parietal cortices relative to animate objects. These findings are consistent with the dissociation between these areas based on sensory- and motor-related object properties, providing further evidence that conceptual object knowledge is housed, in part, in the same neural systems that subserve perception and action.

Adult↗

PubMed1998

Category-specific semantic deficits in focal and widespread brain damage: a computational account.

Category-specific semantic impairments have been explained in terms of preferential damage to different types of features (e.g., perceptual vs. functional). This account is compatible with cases in which the impairments were the result of relatively focal lesions, as in herpes encephalitis. Recently, however, there have been reports of category-specific impairments associated with Alzheimer's disease, in which there is more widespread, patchy damage. We present experiments with a connectionist model that show how "category-specific" impairments can arise in cases of both localized and widespread damage; in this model, types of features are topographically organized, but specific categories are not. These effects mainly depend on differences between categories in the distribution of correlated features. The model's predictions about degree of impairment on natural kinds and artifacts over the course of semantic deterioration are shown to be consistent with existing patient data. The model shows how the probabilistic nature of damage in Alzheimer's disease interacts with the structure of semantic memory to yield different patterns of impairment between patients and categories over time.

Alzheimer Disease↗

PubMed1999

Functional anatomy of perceptual and semantic processing for odors.

The functional anatomy of perceptual and semantic processings for odors was studied using positron emission tomography (PET). The first experiment was a pretest in which 71 normal subjects were asked to rate 185 odorants in terms of intensity, familiarity, hedonicity, and comestibility and to name the odorants. This pretest was necessary to select the most appropriate stimuli for the different cognitive tasks of the second experiment. The second one was a PET experiment in which 15 normal subjects were scanned using the water bolus method to measure regional cerebral blood flow (rCBF) during the performance in three conditions. In the first (perceptual) condition, subjects were asked to judge whether an odor was familiar or not. In the second (semantic) condition, subjects had to decide whether an odor corresponded to a comestible item or not. In the third (detection) condition, subjects had to judge whether the perceived stimulus was made of an odor or was just air. It was hypothetized that the three tasks were hierarchically organized from a superficial detection level to a deep semantic level. Odorants were presented with an air-flow olfactometer, which allowed the stimulations to be synchronized with breathing. Subtraction of activation images obtained between familiarity and control judgments revealed that familiarity judgments were mainly associated with the activity of the right orbito-frontal area, the subcallosal gyrus, the left inferior frontal gyrus, the left superior frontal gyrus, and the anterior cingulate (Brodmann's areas 11, 25, 47, 9, and 32, respectively). The comestibility minus familiarity comparison showed that comestibility judgments selectively activated the primary visual areas. In contrast, a decrease in rCBF was observed in these same visual areas for familiarity judgments and in the orbito-frontal area for comestibility judgments. These results suggest that orbito-frontal and visual regions interact in odor processing in a complementary way, depending on the task requirements.

Adult↗

PubMed2004

Recognition of spoken words: semantic effects in lexical access.

Until recently most models of word recognition have assumed that semantic auditory naming effects come into play only after the identification of the word in question. What little evidence exists for early semantic effects in word recognition lexical decision has relied primarily on priming manipulations using the lexical decision task, and has used visual stimulus presentation. The current study uses semantics auditory stimulus presentation and multiple experimental tasks, and does not use priming. Response latencies for 100 common nouns were found to speech perception depend on perceptual dimensions identified by Osgood (1969): Evaluation, Potency, and Activity. In addition, the two-way interactions between these word recognition dimensions were significant. All effects were above and beyond the effects of concreteness, word length, frequency, onset phoneme characteristics, stress, and neighborhood density. Results are discussed against evidence from several areas of research suggesting a role of behaviorally important information in perception.

Adult↗

PubMed2002

Reduced sensitivity of the N400 and late positive component to semantic congruity and word repetition in left temporal lobe epilepsy.

We studied 14 patients with well-characterized refractory temporal lobe epilepsy (TLE), 7 with right temporal lobe epilepsy (RTE) and 7 with left temporal lobe epilepsy (LTE), on a word repetition ERP experiment. Much prior literature supports the view that patients with left TLE are more likely to develop verbal memory deficits, often attributable to left hippocampal sclerosis. Our main objectives were to test if abnormalities of the N400 or Late Positive Component (LPC, P600) were associated with a left temporal seizure focus, or left temporal lobe dysfunction. A minimum of 19 channels of EEG/EOG data were collected while subjects performed a semantic categorization task. Auditory category statements were followed by a visual target word, which were 50% "congruous" (category exemplars) and 50% "incongruous" (non-category exemplars) with the preceding semantic context. These auditory-visual pairings were repeated pseudo-randomly at time intervals ranging from approximately 10-140 seconds later. The ERP data were submitted to repeated-measures ANOVAs, which showed the RTE group had generally normal effects of word repetition on the LPC and the N400. Also, the N400 component was larger to incongruous than congruous new words, as is normally the case. In contrast, the LTE group did not have statistically significant effects of either word repetition or congruity on their ERPs (N400 or LPC), suggesting that this ERP semantic categorization paradigm is sensitive to left temporal lobe dysfunction. Further studies are ongoing to determine if these ERP abnormalities predict hippocampal sclerosis on histopathology, or outcome after anterior temporal lobectomy.

Adult↗

PubMed2006

Discovering semantic features in the literature: a foundation for building functional associations.

BACKGROUND: Experimental techniques such as DNA microarray, serial analysis of gene expression (SAGE) and mass spectrometry proteomics, among others, are generating large amounts of data related to genes and proteins at different levels. As in any other experimental approach, it is necessary to analyze these data in the context of previously known information about the biological entities under study. The literature is a particularly valuable source of information for experiment validation and interpretation. Therefore, the development of automated text mining tools to assist in such interpretation is one of the main challenges in current bioinformatics research. RESULTS: We present a method to create literature profiles for large sets of genes or proteins based on common semantic features extracted from a corpus of relevant documents. These profiles can be used to establish pair-wise similarities among genes, utilized in gene/protein classification or can be even combined with experimental measurements. Semantic features can be used by researchers to facilitate the understanding of the commonalities indicated by experimental results. Our approach is based on non-negative matrix factorization (NMF), a machine-learning algorithm for data analysis, capable of identifying local patterns that characterize a subset of the data. The literature is thus used to establish putative relationships among subsets of genes or proteins and to provide coherent justification for this clustering into subsets. We demonstrate the utility of the method by applying it to two independent and vastly different sets of genes. CONCLUSION: The presented method can create literature profiles from documents relevant to sets of genes. The representation of genes as additive linear combinations of semantic features allows for the exploration of functional associations as well as for clustering, suggesting a valuable methodology for the validation and interpretation of high-throughput experimental data.

Abstracting and Indexing↗

PubMed2006

Neural correlates of semantic and syntactic processes in the comprehension of case marked pronouns: evidence from German and Dutch.

BACKGROUND: It is well known that both semantic and syntactic information play a role in pronoun resolution in sentences. However, it is unclear what the relative contribution of these sources of information is for the establishment of a coreferential relationship between the pronoun and the antecedent in combination with a local structural case constraint on the pronoun (i.e. case assignment of a pronoun under preposition governing). In a prepositional phrase in German and Dutch, it is the preposition that assigns case to the pronoun. Furthermore, in these languages different overtly case-marked pronouns are used to refer to male and female persons. Thus, one can manipulate biological/syntactic gender features separately from case marking features. The major aim of this study was to determine what the influence of gender information in combination with a local structural case constraint is on the processing of a personal pronoun in a sentence. Event-related brain potential (ERP) experiments were performed in German and in Dutch. In a word by word sentence reading study in German and Dutch, gender congruency between the antecedent and the pronoun was manipulated and/or case assignment by the preposition was violated while ERPs of young native speakers were recorded. RESULTS: The German and the Dutch ERP data showed an enlarged negativity broadly distributed starting approximately 350 ms after onset of the pronoun followed by a late positivity for gender violations. For syntactic incongruencies without gender violations only a positivity was present. The Dutch data showed an earlier onset of the positivity in comparison to German. CONCLUSION: Finding negativities and positivities for conditions with a gender violation indicates that pronoun resolution with gender incongruency between the pronoun and the antecedent suffers from semantic as well as syntactic integration problems. The presence of a positivity for the syntactically incongruent conditions without gender violations suggests that the processing of incorrect case marking without a gender violation gives rise to syntactic but not semantic integration problems. We suggest that the more prominent case violation in Dutch caused the earlier onset of the positivity in the Dutch study. In addition, the pattern of ERP effects shows that both case and gender information are used almost immediately implying that the local structural constraint affects the resolution process with more processing activity than for a pronoun of which only one source of information is violated or incongruent.

Adult↗

PubMed2003

The syntax and semantics of the PROforma guideline modeling language.

PROforma is an executable process modeling language that has been used successfully to build and deploy a range of decision support systems, guidelines, and other clinical applications. It is one of a number of recent proposals for representing clinical protocols and guidelines in a machine-executable format (see ). In this report, the authors outline the task model for the language and provide an operational semantics for process enactment together with a semantics for expressions, which may be used to query the state of a task during enactment. The operational semantics includes a number of public operations that may be performed on an application by an external agent, including operations that change the values of data items, recommend or make decisions, manage tasks that have been performed, and perform any task state changes that are implied by the current state of the application. Disclosure: PROforma has been used as the basis of a commercial decision support and guideline technology Arezzo (Infermed, London, UK; details in text).

Decision Support Systems, Clinical↗

PubMed2006

Use of SNOMED CT to represent clinical research data: a semantic characterization of data items on case report forms in vasculitis research.

OBJECTIVE: To estimate the coverage provided by SNOMED CT for clinical research concepts represented by the items on case report forms (CRFs), as well as the semantic nature of those concepts relevant to post-coordination methods. DESIGN: Convenience samples from CRFs developed by rheumatologists conducting several longitudinal, observational studies of vasculitis were selected. A total of 17 CRFs were used as the basis of analysis for this study, from which a total set of 616 (unique) items were identified. Each unique data item was classified as either a clinical finding or procedure. The items were coded by the presence and nature of SNOMED CT coverage and classified into semantic types by 2 coders. MEASUREMENTS: Basic frequency analysis was conducted to determine levels of coverage provided by SNOMED CT. Estimates of coverage by various semantic characterizations were estimated. RESULTS: Most of the core clinical concepts (88%) from these clinical research data items were covered by SNOMED CT; however, far fewer of the concepts were fully covered (that is, where all aspects of the CRF item could be represented completely without post-coordination; 23%). In addition, a large majority of the concepts (83%) required post-coordination, either to clarify context (e.g., time) or to better capture complex clinical concepts (e.g., disease-related findings). For just over one third of the sampled CRF data items, both types of post-coordination were necessary to fully represent the meaning of the item. CONCLUSION: SNOMED CT appears well-suited for representing a variety of clinical concepts, yet is less suited for representing the full amount of information collected on CRFs.

Clinical Medicine↗

PubMed2001

Event-related potentials and picture-word naming: effects of attention and semantic relation for children and adults.

Event-related potentials (ERPs) were recorded from children, 9 to 13 years of age, while they named words and pictures. The words and pictures were presented individually and in superimposed picture-word pairs in which the meaning of the words and pictures was either congruent, semantically associated, or incongruent. Both words and pictures elicited large amplitude negative waves (N450) at anterior electrode sites. The amplitude of this N450 wave was larger for individually presented pictures than for words. N450 amplitude was also larger when naming pictures than when naming words in the superimposed arrays, an effect that is attributed to differences in attentional demand required to name pictures rather than to exogenous stimulus characteristics. No significant effects of semantic incongruity were observed. These ERP waveforms for children differ from those observed for adults who exhibited positive amplitude waves to individually presented pictures and who also exhibited semantic incongruity effects.

Adult↗

PubMed2001

Cortical degeneration associated with phonologic and semantic language impairments in AD.

OBJECTIVE: To compare the pattern of cortical degeneration associated with different language deficits in cases of AD. METHODS: Cases for detailed neuropathologic analysis (Patients 1 and 2) were selected because of their detailed clinical and neuropsychological assessments of language dysfunction in AD. Patient 1 had severe phonologic impairment with relatively preserved semantic aspects of language. Patient 2 had severe semantic language impairment with relatively preserved phonologic skills. The tissue volume of cortical regions associated with speech and language function was measured using standardized three-dimensional techniques. Neuronal areal fraction was also measured from histologic tissue samples. The degree of volume atrophy and neuronal loss was calculated in comparison to control measures (n = 10 men and 11 women). Measurements more than 2 SD from controls were considered abnormal. RESULTS: Both AD cases had significant degeneration of the superior temporal gyrus and area 37. Cortical language regions affected only in Patient 1 included the anterior and posterior insula and part of Broca's area. In contrast, Patient 2 had a greater degree of degeneration in the temporal gyri and their white matter connections with the hippocampal/entorhinal complex. CONCLUSIONS: Variable patterns of neurodegeneration underlie the clinical differences observed in patients with AD. Disconnection within the temporal lobe appears associated with semantic language difficulties, whereas disconnection of the anterior and posterior language areas appears associated with phonologic and grammatical impairment.

Aged↗

PubMed2000

Syntactic and semantic processing in Hebrew readers with prelingual deafness.

The experimenter investigated the effect of semantic clues on the reading comprehension of deaf and hearing Israeli children. Two groups of students with prelingual deafness, and a hearing control group, were asked to read syntactically simple and syntactically relative sentences of varying semantic plausibility. Sixteen of the participants who were deaf (mean grade 6.9) had been trained orally, using spoken language as their principal means of communication at home and at school. Another 16 students with deafness (mean grade 6.9), all of them children of deaf parents, had acquired sign language as their primary language. The mean grade of the hearing control group was 6.5. The results suggest that, in contrast to the case with hearing individuals, reading comprehension in individuals with prelingually acquired deafness, regardless of communication background, is predominantly determined by the semantic processing of content words, with only minor attention given to the processing of the syntactic structure of the text.

Child↗

PubMed1975

Immediate recall fo semantically varied "sentences" by learning-disabled adolescents.

The immediate recall of 20 semantically and syntactically varied sentences was assessed and compared for 30 learning-disabled and 30 academically achieving adolescents. Learning-disabled adolescents repeated significantly fewer of the sentences verbatim than their achieving age peers. They exhibited significant reductions in the recall of sentences which violated semantic (selectional) rules, contained correctly and incorrectly sequenced modifier-strings, contained a random word-setting, or were syntactically complex. Perseveration errors occured more frequently among the learning-disabled adolescents than among the achievers and inter-sentence perseverative errors were exhibited only by those who were learning disabled. The rank order of difficulty for the sentences agreed for the two groups, suggesting primarily quantitative reductions in the immediate recall by the learning-disabled adolescents. The findings suggest that learning-disabled adolescents depend heavily upon semantic aspects for language processing, experience immediate memory and sequencing problems for modifier-strings, and exhibit a prevalence of interfering perseverative responses.

Adolescent↗

PubMed1975

Semantic desensitization: language conditioning or demand characteristics manipulation?

Previous studies in language conditioning, especially those called semantic desensitization, have shown changes in self-report, behavioral measures, and the semantic meaning of the target concept following treatment. This last has been proposed as a causal variable but experimental and control groups differed greatly in terms of their demand characteristics. The present study included a placebo group with demand characteristics similar to those of the control group. The target area was self-concept (18 male Ss, 9 female Ss). Significant changes in self-report and actual performance with a hand dynamometer were obtained but these were as great for the placebo group as for the experimental groups. It was suggested that factors other than conditioning are of importance in semantic desensitization.

Awareness↗

PubMed1991

Contribution of perceptual and lexical-semantic errors to the naming impairments in Alzheimer's disease.

The contribution of perceptual and semantic processing deficits to naming-test performance by Alzheimer's Disease subjects was examined. Groups of 34 Alzheimer subjects and 25 elderly controls completed tests of naming standard line drawings and naming perceptually degraded figures, and a test of verbal fluency for a specific semantic category. Alzheimer subjects were impaired on all measures and, when their naming-test errors were analyzed, they showed higher proportions of perceptual errors and failures to respond. Further, considerable variability in the proportions of different types of error was found both among subjects and among test items. These findings indicate that poor naming-test performance cannot necessarily be attributed to a specific deficit in semantic processing. Also, the discrepancies between previous reports of the naming deficits in Alzheimer's Disease may reflect differences in task difficulty and item selection that were apparent in this study.

Aged↗

PubMed1994

Orthographic, phonologic, and semantic processing in reading disabled and nondisabled subjects.

In this study the confusability paradigm of Byrne and Shea and Waterman and Lewandowski was modified to include an orthographic condition made possible by presenting stimuli visually rather than aurally. The confusability tasks included a pseudoword-recognition task with only phonologic and orthographic information available for coding and a word-recognition task with phonologic, semantic, and orthographic information available for coding. 20 poor and 20 good readers (13 to 18 years of age) were asked to report whether stimuli had been presented a second time in two continuous lists (pseudoword and word). In contrast to previous work, phonologic confusability was not observed for either group, whereas orthographic confusability was noted for both groups on both tasks. Semantic confusability occurred for both groups on the word task. On these tasks which triggered orthographic and semantic processing (errors) poor readers performed comparably to good readers, suggesting that on a confusability task presented visually they were not disadvantaged.

Achievement↗

PubMed1995

An event-related potential study of the effects of semantic deviations: an application of a method of sequential-part presentation.

The present study was designed to evaluate the effects of semantic deviations of picture stimuli by applying a method of sequential-part presentations. S1 stimuli were 10 pictures of animals which were divided into 7 x 7 portions and successively presented in random order. S2 stimuli were three types of pictures (A, the same as S1; B, semantically the same but physically different from S1; and C, both semantically and physically different from S1). Subjects were required to name S1 verbally after seeing S2. The largest N400 components of the event-related potential were elicited for Category C of S2, whereas large LPCs were elicited for Categories B and C. This suggests that a method of sequential-part presentations is effective for eliciting the N400 component of the event-related potential for picture stimuli.

Adult↗

PubMed2004

School children's responses on a semantic differential over a 10-year span.

A semantic differential scale was administered to 208 school children when they were in the second, fourth, sixth, eighth, tenth, and twelfth grades. Their perceptions towards two concepts were measured, Education (going to school) and Work (having a job). Each semantic differential scale had 15 adjective pairs and reflected the three underlying factors of Evaluative, Potency, and Activity. Because the study was conducted for 10 years (ages seven to 18), the changing cognitive developmental stages of the children were expected to influence factor analytic and reliability results. Confirmatory factor analysis, which forced the data into three factors, did not clearly identify the expected three factors, although more items loaded on the three factors with age. An exploratory factor analysis identified a trend across grades from six to four factors over time. Reliability also improved across age groups. Caution should be exercised when using the semantic differential with young children in investigations of abstract concepts.

Adolescent↗