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PubMedDate not supplied

[Evoked potential as a measure of perceptive and semantic differences].

The informational significance of human perceptive and semantic evoked potentials to an abrupt change in non-verbal or verbal stimuli, respectively, is discussed. The amplitudes of perceptive and semantic evoked potentials were shown to be positively correlated with subjective estimates of differences between these stimuli. Multidimensional scaling of amplitude matrices and subjective estimates of differences after pair-wise replacement of the stimuli showed that colors and color names were encoded by excitation vectors of equal lengths in four-dimensional spherical space of colors. Color differences were shown to be equal to absolute values of their excitation vectors, whereas semantic differences in color names turned to be determined by the absolute values of vector differences between color memory traces represented as long-term memory excitation vectors. The data were summarized in the framework of cognitive spherical model.

Evoked Potentials, Auditory↗

PubMed2006

A functional MRI study: cerebral laterality for lexical-semantic processing and human voice perception.

BACKGROUND AND PURPOSE: Language dominance research using functional neuroimaging has made important contributions to clinical applications. Nevertheless, although recent neuroimaging studies demonstrated right-lateralized activation by human voice perception, the influence of voice perception in terms of language dominance has not been adequately studied. We aimed to accurately clarify language dominance for lexical-semantic processing in the temporal cortices by focusing on human voice perception. METHODS: Thirty normal right-handed subjects were scanned by functional MR imaging while listening to sentences (SEN), reverse sentences (rSEN), and identifiable nonvocal sounds (SND). We investigated cerebral activation and the distribution of individual Laterality Index under 3 contrasts: rSEN-SND, SEN-SND, and SEN-rSEN. RESULTS: The rSEN-SND contrast, including human voice perception, revealed right-lateralized activation in the anterior temporal cortices. Both SEN-SND and SEN-rSEN contrasts, including lexical-semantic processing, showed left-lateralized activation in the inferior and middle frontal gyrus and middle temporal gyrus. The SEN-rSEN contrast, without the influence of human voice perception, showed no temporal activation in the right hemisphere. Symmetrical or right-lateralized activation was observed in 22 of 27 subjects (81.4%) under the rSEN-SND contrast in the temporal cortices. Although 9 of 27 subjects (33.3%) showed symmetrical or right-lateralized activation under the SEN-SND contrast in the temporal cortices, all subjects showed left-lateralized activation under the SEN-rSEN contrast. CONCLUSION: Our results demonstrated that right-lateralized activation by human voice perception could mask left-lateralized activation by lexical-semantic processing. This finding suggests that the influence of human voice perception should be adequately taken into account when language dominance is determined.

Adult↗

PubMed1987

Focal and diffuse memory activation assessed by localized indicators of CNS metabolism: the semantic-episodic memory distinction.

Methods for in-vivo measurement in humans of local brain activation are reviewed, to assess their potential contribution to the understanding of the brain organization of memory. Methodologically, it is argued that the instructive studies are those: (a) using fully normal subjects; (b) using sufficient sample sizes to account statistically for individual differences; and (c) using properly designed control tasks to isolate relevant independent variables that determine the brain response. The review of emerging data concentrates on the regional cerebral blood flow literature and proposes certain hypotheses for further test, based on extant findings. These include: (a) that hyperfrontality of cortical activation signals the type of processing that converts material from episodic to semantic memory; (b) that semantic remembering itself is likely to engage focal association areas relevant to the particular task (e.g. Wernicke's area in language tasks); but (c) that episodic remembering, even when task components such as language are controlled, will engender a less focal but more diffuse activation pattern than would a control semantic remembering task.

Brain↗

PubMed1995

Language-related field potentials in the anterior-medial temporal lobe: II. Effects of word type and semantic priming.

Field potentials were recorded from intracranial electrodes in humans to study the role of the anterior medial temporal lobe (AMTL) in language-related processing. Subjects viewed lists of words in which orthography and word type varied, or in which words were primed by semantic associates. Large negative field potentials were elicited within the AMTL by isolated words. The amplitude and intracranial distribution of these AMTL field potentials were consistent with those in our previous study in which anomalous sentence-ending words were used as stimuli (McCarthy et al., in press). The neocortex, in the region of the collateral sulcus and anterior fusiform gyrus, was identified as the likely neural generator of this field potential. The AMTL field potential was diminished by semantic priming, and was larger for words with semantic content than for words serving grammatical function. Orthographically illegal nonwords did not elicit this field potential. The N400 scalp event-related potential (ERP) has been shown to respond in the same manner to these task manipulations (Nobre and McCarthy, 1994), and, thus, the AMTL field potential was proposed to contribute to the generation of N400. The possible roles in language processing reflected by the AMTL field potential were considered.

Action Potentials↗

PubMed1978

Simplified use of the semantic differential to measure psychotherapy outcome.

To initially establish the validity and utility of a simplified use of the Semantic Differential to measure psychotherapy outcome, 14 clients were administered, before and after 15 sessions of individual psychotherapy, the Semantic Differential and a symptom checklist. As predicted, results indicated that change of clients' self-constructs in a positive direction was associated with symptom reduction. Implications for psychotherapy research are discussed.

Adult↗

PubMed2005

Object naming and semantic fluency among individuals with genetic risk for Alzheimer's disease.

OBJECTIVES: This study longitudinally examined the object naming and semantic fluency of individuals who are at risk for developing Alzheimer's disease (AD) by virtue of having APOE-4 or a family history of AD. METHODS: A total of 108 participants (40 with a family history of AD and 43 with APOE-4) completed the Boston Naming Test and the Animal Naming task at initial assessment and after two years. RESULTS: At baseline, object naming was significantly lower for those with both risk factors, F(2, 99) = 5.72, p < 0.01, but those with either risk factor had significantly lower scores at follow-up, F(2, 99) = 3.41, p < 0.05. Semantic fluency (animal naming) was reduced among subjects with the APOE-4 allele at baseline, F(1, 100) = 4.02, p < 0.05, but it was not associated with either risk factor at follow-up. CONCLUSIONS: These deficits may be associated with a prodromal risk for AD and may serve as pre-symptomatic markers for the development of AD.

Aged↗

PubMed2001

The semantic interference effect in the picture-word paradigm: an event-related fMRI study employing overt responses.

We used event-related functional magnetic resonance imaging (fMRI) to investigate neural responses associated with the semantic interference (SI) effect in the picture-word task. Independent stage models of word production assume that the locus of the SI effect is at the conceptual processing level (Levelt et al. [1999]: Behav Brain Sci 22:1-75), whereas interactive models postulate that it occurs at phonological retrieval (Starreveld and La Heij [1996]: J Exp Psychol Learn Mem Cogn 22:896-918). In both types of model resolution of the SI effect occurs as a result of competitive, spreading activation without the involvement of inhibitory links. These assumptions were tested by randomly presenting participants with trials from semantically-related and lexical control distractor conditions and acquiring image volumes coincident with the estimated peak hemodynamic response for each trial. Overt vocalization of picture names occurred in the absence of scanner noise, allowing reaction time (RT) data to be collected. Analysis of the RT data confirmed the SI effect. Regions showing differential hemodynamic responses during the SI effect included the left mid section of the middle temporal gyrus, left posterior superior temporal gyrus, left anterior cingulate cortex, and bilateral orbitomedial prefrontal cortex. Additional responses were observed in the frontal eye fields, left inferior parietal lobule, and right anterior temporal and occipital cortex. The results are interpreted as indirectly supporting interactive models that allow spreading activation between both conceptual processing and phonological retrieval levels of word production. In addition, the data confirm that selective attention/response suppression has a role in resolving the SI effect similar to the way in which Stroop interference is resolved. We conclude that neuroimaging studies can provide information about the neuroanatomical organization of the lexical system that may prove useful for constraining theoretical models of word production.

Adult↗

PubMed2006

Effects of a benzodiazepine on free recall of semantically related words.

Although it is widely known that benzodiazepines impair episodic memory, few studies have investigated their effects upon specific processes involved in free recall. This study evaluated the acute effects of flunitrazepam (1.0 mg; 1.3 mg) and placebo in healthy volunteers on immediate and delayed free recall of word lists considering serial positions as well as semantic relations between words inserted in the middle of the lists (e.g. milk-cheese-butter). Flunitrazepam promoted a global amnestic effect, impairing recall in all serial positions except the last words (recency effect). Primacy and recency effects were preserved as indexed, respectively, by larger recall of the first and last words in relation to adjacent items. Facilitation in recall of semantically related words was not impaired by the drug when compared to recall in adjacent positions, in spite of a dose-dependent diminution of the number of words recalled also in mid-list positions. Flunitrazepam-induced deficits were interpreted as impairment in the formation of new associations between items, or groups of items in the case of related words, and context.

Adult↗

PubMed1994

Event-related brain potentials reflect semantic priming in an object decision task.

Subjects made speeded object decisions about target line drawings which were preceded by semantically related or unrelated prime line drawings. One hundred of the targets depicted real objects and 50 others were unrecognizable non-objects. Similar to a recent picture-matching study, the ERPs from this study generated a larger negativity for unrelated than for related target pictures, between 325 and 550 msec (N400). Although these differences had a similar time course to those seen for the N400 component in semantic priming lexical decision tasks, they were more frontally distributed and were larger over the left rather than the right hemisphere. Non-objects, which were the picture equivalent of pseudowords, produced an even larger negativity with a somewhat different distribution. The results are discussed with regards to recent claims about amodal conceptual memory processes.

Adult↗

PubMed1999

Subcortical mechanisms in language: lexical-semantic mechanisms and the thalamus.

Four previously published cases of dominant thalamic lesion in which the author has participated are reviewed to gain a better understanding of thalamic participation in lexical-semantic functions. Naming deficits in two cases support Nadeau and Crosson's (1997) hypothesis of a selective engagement mechanism involving the frontal lobes, inferior thalamic peduncle, nucleus reticularis, and other thalamic nuclei, possibly the centromedian nucleus. This mechanism selectively engages those cortical areas required to perform a cognitive task, while maintaining other areas in a state of relative disengagement. Deficits in selective engagement disproportionately affect lexical retrieval based on semantic input, as opposed to lexical and sublexical processes, because the former is more dependent upon this attentional system. The concept of selective engagement is also useful in understanding thalamic participation in working memory, as supported by data from one recent functional neuroimaging study. Other processes also may be compromised in more posterior thalamic lesions which damage the pulvinar but not other components of this selective engagement system. A third case with aphasia after a more superior and posterior thalamic lesion also had oral reading errors similar to those in neglect dyslexia. The pattern of deficits suggested a visual processing problem in the early stages of reading. The fourth case had a category-specific naming deficit after posterior thalamic lesion. Taken together, the latter two cases indicate that the nature of language functions in more posterior regions of the dominant thalamus depends upon the cortical connectivity of the thalamic region. Together, findings from the four cases suggest that thalamic nuclei and systems are involved in multiple processes which directly or indirectly support cortical language functions.

Aphasia↗

PubMed1995

Decline in homophone spelling associated with loss of semantic influence on spelling in Alzheimer's disease.

The homophone spellings of 20 subjects with Alzheimer's disease (AD) and mild dementia were compared to those of matched normal controls. Both groups were tested once (Time 1) and then again 9 months to 1 year later (Time 2). At Time 1, AD subjects misspelled more homophones than the control group and the discrepancy between the two groups' performances significantly increased by Time 2. Two types of errors were tabulated: homophone confusions (i.e. an inappropriate yet correctly spelled homophone given the context, such as spelling doe, given the context "bake the bread dough") and other spelling errors (e.g. doue, dogh). The relationship between homophone confusions and confrontation naming increased from Time 1 to Time 2. In contrast, the relationship between the number of spelling errors (that were not homophone confusions) and confrontation naming performance was not significant at Time 2. One subgroup of 3 subjects showed an increase in homophone confusions and confrontational naming errors and not more spelling errors. Another subgroup of 4 subjects showed neither an increase in homophone confusions nor in confrontational naming errors, but did show an increase in spelling errors. Based on these results, we suggest that homophone confusions are primarily due to impairment of semantic access to a functional orthographic output lexicon. Other spelling errors may reflect post-linguistic spelling deficits without a significant change in the use of semantic input for spelling homophones.

Aged↗

PubMed1995

The production of semantic paralexias in a Spanish-speaking aphasic.

A case of a Spanish-speaking aphasic patient who produced a great number of semantic paralexias in reading aloud and who showed other symptoms consistent with the diagnosis of deep dyslexia is presented. In this study, (a) the production of semantic paralexias and the features of the deep dyslexia syndrome which have only recently begun to be studied in Spanish-speaking patients, are analyzed; and (b) the "obligatory character of phonological mediation in the reading of Spanish proposed by some authors is discussed.

Anomia↗

PubMed1997

Finding the locus of semantic satiation: an electrophysiological attempt.

The present study examined the effect of massed repetition of an initial category name upon the subsequent semantic categorization of a target word by means of an electrophysiological measure of semantic processing: the N400. Results showed the classic N400 effect, whereby evoked potentials were more negative for targets that were not members of the repeated category than for member targets. Moreover, repetition of the category name led to an increased and sustained positivity. The N400 effect was not modified, however, by repetition. Hence, insomuch as the N400 reflects meaning integration processes, these results do not support the hypothesis that massed repetition exerts its influence at the level of meaning integration.

Adult↗

PubMed1997

Phonological, semantic, and mediated priming in aphasia.

An auditory lexical decision task was conducted to examine rhyme, semantic, and mediated priming in nonfluent and fluent aphasic patients and normal controls. Overall, monosyllabic word targets were responded to faster when preceded by rhyming word and nonword primes than unrelated primes. Similarly, semantically related primes facilitated lexical decisions to word targets. No evidence of mediated priming emerged. Results for individual subjects suggest differences in patterns across the subject groups. Implications of the findings for the integrity of lexical access in aphasic patients are considered.

Adult↗

PubMedDate not supplied

Morpholexical access and naming: the semantic interpretability of new root-suffix combinations.

In two experiments, pseudowords made up of Italian roots and derivational suffixes were investigated. In visual lexical decision, the licensing of a new root-suffix combination was affected by its semantic interpretability, but not by its grammatical appropriateness. By contrast, the degree of interpretability of new root-suffix combinations did not affect naming. However, and irrespective of differences in interpretability, pseudowords made up of two morphemes were named more efficiently than pseudowords with no morphological constituency. These results, while showing the involvement of the semantic component in the licensing process, also show its dissociability in lexical naming, thus suggesting morpholexical nonsemantic naming.

Cognition↗

PubMed1999

Qualitative hemispheric differences in semantic category matching.

A unilateral category matching task with words as stimuli was employed to investigate semantic processing in the right and left hemispheres (RH, LH). An overall right visual field (RVF)/LH dominance was observed and performances were better than chance, also in the left visual field (LVF)/RH. A qualitative analysis of reaction times with individual differences multidimensional scaling (INDSCAL) revealed that LVF/RH INDSCAL solutions were significantly more differentiated in structure than RVF/LH solutions in terms of number and size of dimensions. These findings support a depth of activation hypothesis of hemispheric processing, with the LH rapidly and focally and the RH slowly and diffusely activating the semantic network.

Adult↗

PubMed2000

Dissociation of semantic and phonological errors in naming.

We report the naming performance of a fluent aphasic, DP, who shows a striking dissociation between semantic and phonological (nonword) errors: he produced numerous semantic errors but virtually no phonological errors. DP's pattern of performance is the reverse of that reported for patient DM (Caramazza, Papagno, & Ruml, 2000), who only made phonological errors in a naming task. These patterns of performance are inconsistent with the proposal by Dell, Schwartz, Martin, Saffran, and Gagnon (1997) that the naming deficit in fluent aphasia is the result of global damage to all levels of the lexical access system and support instead the hypothesis that brain damage can selectively disrupt distinct subcomponents of the lexical processing system.

Aphasia, Wernicke↗

PubMed2001

Noun-verb differences? a question of semantics: a response to shapiro and caramazza.

We presented a new model using the sensory/functional theory of semantic category deficits to explain noun/verb deficits in aphasia. The predictions arising from this model were tested on a small number of patients exhibiting grammatical and/or semantic category specific deficits in picture naming. The results lent support for the theory presented. Shapiro and Caramazza (this issue) raised several objections to this theory (which they call the "extended sensory functional theory," or ESFT). In this article we address their concerns about the validity of the ESFT and conclude that it is indeed a useful model that provides a parsimonious explanation for many diverse patterns of deficits.

Aphasia↗