Patterns of comprehension and production of nouns and verbs in agrammatism: implications for lexical organization

This study examined the relationship between verb retrieval and verb-argument-structure properties in seven agrammatic aphasic patients using tasks requiring access to the verb's lexicon for both comprehension- and productionlike processes. Results showed intact comprehension of both nouns and verbs and noun naming, but impaired naming of verbs. Subjects also demonstrated near-normal performance on a grammaticality judgment task involving verb-argument-structure violations but were impaired in categorizing verbs by type (based on number of obligatory arguments). In both naming and categorization conditions, a hierarchy of verb difficulty emerged. Subjects were more accurate in naming/categorizing one-place verbs than two-place verbs and more accurate in naming/categorizing two-place verbs than three-place verbs. The pattern of selective impairment in lexical access/retrieval supports the hypothesis that one dimension of normal lexical organization is by form class. The results also suggest that no necessary relationship exists between production difficulties and comprehension of nouns/verbs in agrammatism. Further, the performance pattern noted supports the claim that verb-argument-structure properties, an important component of the verb lexicon, influence verb production at the single-word and at the sentence level. Subjects' performance on different tasks suggests that the locus of breakdown in the verb-retrieval processes for productionlike tasks may be in accessing information at the lemma level of representation as per Bock's model (1995) of sentence production.     

The reliability of the time-sharing paradigm

The primary purpose of this study was to investigate the reliability of the time-sharing paradigm as a function of the age of the child and the concurrent speaking task employed. Subjects were 40 normal right-handed children, 10 at each of four age levels: 3, 5, 7, and 9. Each subject was presented with three concurrent speaking tasks, syllable repetition, sentence repetition, and story telling. There were control tapping and verbal conditions as well. The entire experimental procedure was administered two times within a 2-week interval. The principal finding of the study was that children were more likely to show the predicted asymmetry on the first administration of the paradigm than on the second one. The sentence repetition task was the one most likely to show the predicted asymmetry between hands, though children showed the most consistent performance on the syllable repetition task. Based on these findings, it was suggested that the time-sharing paradigm might not be particularly reliable in showing the predicted asymmetry in repeated administration of the same tasks with the same linguistic stimuli.     

Consequences of brain tumour resection on emotion recognition

Emotion processing impairments are common in patients undergoing brain surgery for fronto-temporal tumour resection, with potential consequences on social interactions. However, evidence is controversial concerning side and site of lesions causing such deficits. This study investigates visual and auditory emotion recognition in brain tumour patients with the aim of clarifying which lesion sites are related to impairments in emotion processing from different modalities. Thirty-four patients were evaluated, before and after surgery, on facial expression and emotional prosody recognition; voxel-based lesion–symptom mapping (VLSM) analyses were performed on patients’ post-surgery MRI images. Results showed that patients’ performance decreased after surgery in both visual and auditory modalities, but, in general, recovered 3 months after surgery. In facial expression recognition, left brain-damaged patients showed greater post-surgery deterioration than right brain-damaged ones, whose performance specifically decreased for sadness and fear. VLSM analysis revealed two segregated areas in the left hemisphere accounting for post-surgery scores for happy (fronto-temporo-insular region) and surprised (middle frontal gyrus and inferior fronto-occipital fasciculus) facial expressions. Our findings demonstrate that surgical removal of tumours in the fronto-temporal region produces impairment in facial emotion recognition with an overall recovery at 3 months, suggesting a partially different representation of positive and negative emotions in the left and right hemispheres for visually – but not auditory – presented emotions; moreover, we show that deficits in specific expression recognition are associated with discrete lesion locations.     

计算的脑机制研究进展

采用计算任务来探讨脑机制已成为国外研究大脑活动的重要领域。该文阐述了神经心理学和脑成像领域有关计算的脑机制研究。神经心理学及脑损伤的研究结果表明,大脑两侧顶下小叶和左前额叶与计算加工有关。ERP、PET和fMRI脑成像研究结果显示,数字命名与比较、心算、精算和估算等不同计算任务,其所激活的脑部位有所差异,但是大脑两侧顶下小叶和左前额叶可能是计算加工的主要脑部位。由于研究材料、方法和程序的不同,大脑皮层的广泛区域都有可能参与计算加工。     

The roles of stimulus repetition and hemispheric activation in visual half-field asymmetries

Hardyck, Tzeng, and Wang (1978, Brain and Language, 5, 56–71) hypothesized that ample repetition of a small number of stimuli is required in order to obtain VHF differences in tachistoscopic tasks. Four experiments, with varied levels of repetition, were conducted to test this hypothesis. Three experiments utilized the general task of object-picture naming and one utilized a word-naming task. Naming latencies constituted the dependent measure. The results demonstrate that for the object-naming paradigm repetition is required for RVF superiority to emerge. Repetition was found to be unnecessary for RVF superiority in the word-naming paradigm, with repetition actually reducing RVF superiority. Experiment I suggested the possibility that RVF superiority developed for the second half of the trials as a function of practice or hemispheric activation, regardless of repetition level. Subsequent experiments, better designed to assess this possibility, clearly refuted it. It was concluded that the effect of repetition depends on the processing requirements of the task. We propose that, for tasks which can be processed efficiently by one hemisphere, the effect of repetition will be to reduce VHF asymmetries; but tasks requiring substantial processing by both hemispheres will show shifts to RVF superiority as a function of repetition.     

Evaluation of narrative abilities in patients suffering from Duchenne Muscular Dystrophy

The present work investigated cognitive, linguistic and narrative abilities in a group of children suffering from Duchenne Muscular Dystrophy, an allelic X-linked recessive disorder caused by mutations in the gene encoding dystrophin. The patients showed mildly reduced IQ with lower Verbal than Performance Intelligence Quotient and were mildly affected in visual attention and short-term memory processing. At the linguistic assessment, neither receptive (word comprehension) nor expressive (naming tasks and fluency) lexical abilities were impaired. However, their narratives were qualitatively inferior with respect to those produced by a group of typically developing children. Their speech samples were characterized by the presence of fewer verbs and complete sentences. It is suggested that the reduced production of complete sentences is due to a selective problem in verb argument structure generation. Since the lack of dystrophin is assumed to produce effects on the maturation of the cerebellum, whose involvement has been recently suggested in verb and syntactic processing, these findings may lend indirect support to the hypothesis of a cerebellar-cortical circuit specialized in verb and sentence production.     

Eye–voice span during rapid automatized naming of digits and dice in Chinese normal and dyslexic children

We measured Chinese dyslexic and control children's eye movements during rapid automatized naming (RAN) with alphanumeric (digits) and symbolic (dice surfaces) stimuli. Both types of stimuli required identical oral responses, controlling for effects associated with speech production. Results showed that naming dice was much slower than naming digits for both groups, but group differences in eye‐movement measures and in the eye–voice span (i.e. the distance between the currently fixated item and the voiced item) were generally larger in digit‐RAN than in dice‐RAN. In addition, dyslexics were less efficient in parafoveal processing in these RAN tasks. Since the two RAN tasks required the same phonological output and on the assumption that naming dice is less practiced than naming digits in general, the results suggest that the translation of alphanumeric visual symbols into phonological codes is less efficient in dyslexic children. The dissociation of the print‐to‐sound conversion and phonological representation suggests that the degree of automaticity in translation from visual symbols to phonological codes in addition to phonological processing per se is also critical to understanding dyslexia.     

Oral language deficits in dyslexic children: weaknesses in working memory and verbal planning

This paper focuses on the relationships among language processing (word- and sentence-level), working memory, and verbal/nonverbal linguistic output. The study examined oral language abilities in a group of 26 French-speaking dyslexic children, compared to two control groups (26 normally developing age-matched children and 26 normally developing younger children). The experimental procedure consisted of tasks involving auditory memory skills (digit span, unfamiliar word repetition, sentence repetition), word retrieval (with semantic, phonological and grammatical criteria), and sentence processing (with verbal and act-out production). The major findings reveal that (a) compared with their age-mates, the dyslexic children exhibited a significant deficit affecting all tasks; and (b) the dyslexic children and the younger controls performed similarly on several tasks. The results are consistent with the processing limitation hypothesis and suggest that the core deficit is the formulation of cognitive plans from auditory input to verbal output.     

Compound word effects differ in reading,on-line naming,and delayed naming tasks

Bimorphemic compound words (e.g.,blueberry), bimorphemic suffixed words (e.g.,ceaseless), and monomorphemic controls (e.g.,arthritis) were read in neutral sentence contexts in Experiment 1. The main result revealed longer first fixation durations on compound words than on control and suffixed words. Different effects emerged when naming tasks were used. An on-line naming task revealed substantially shorter naming latencies for compound words than for control and suffixed words. Naming latencies for compound and control words were equivalent in a delayed naming task. These results indicate that on-line naming latencies and word-viewing durations may yield diverging results. They also suggest that activation of constituent words of compound words occurs independently from the specification of conventional word meanings.     

Verbal Fluency,Semantics, Context and Symptom Complexes in Schizophrenia

Lexical-semantic access and retrieval was examined in 15 adults diagnosed with schizophrenia and matched controls. This study extends the literature through the inclusion of multiple examinations of lexical-semantic production within the same patient group and through correlating performance on these tasks with various positive and negative clinical symptoms. On tasks of verbal fluency, meaning generation, sentence production using contextual information and confrontation naming, participants with schizophrenia made significantly more semantic errors on naming tasks; produced fewer meanings for homophones; produced fewer items on semantic, phonological, cued and switching fluency tasks; and produced more errors on sentence production tasks when compared to healthy controls. Significant correlations were also observed between ratings of psychomotor poverty and measures of semantic production and mental inflexibility. This study has provided additional evidence for deficits in lexical-semantic retrieval which are not due to underlying semantic store degradation, do not involve phonological based retrieval, and at the level of sentence generation appear to vary as a function of the contextual constraints provided.     

The processing of lexical stress during visual word recognition: typicality effects and orthographic correlates

Many studies that have examined reading at the single-word level have been restricted to the processing of monosyllabic stimuli, and, as a result, lexical stress has not been widely investigated. In the experiments reported here, we used disyllabic words and nonwords to investigate the processing of lexical stress during visual word recognition. In Experiments 1 and 2, we found an effect of stress typicality in naming and lexical decision. Typically stressed words (trochaic nouns and iambic verbs) elicited fewer errors than atypically stressed words (iambic nouns and trochaic verbs). In Experiment 3, we carried out an analysis of 340 word endings and found clear orthographic correlates of both grammatical category and lexical stress in word endings. In Experiment 4, we demonstrated that readers are sensitive to these cues in their processing of nonwords during two tasks: sentence construction and stress assignment. We discuss the implications of these findings with regard to psycholinguistic models of single-word reading.     

The processing of lexical stress during visual word recognition: Typicality effects and orthographic correlates

Many studies that have examined reading at the single-word level have been restricted to the processing of monosyllabic stimuli, and, as a result, lexical stress has not been widely investigated. In the experiments reported here, we used disyllabic words and nonwords to investigate the processing of lexical stress during visual word recognition. In Experiments 1 and 2, we found an effect of stress typicality in naming and lexical decision. Typically stressed words (trochaic nouns and iambic verbs) elicited fewer errors than atypically stressed words (iambic nouns and trochaic verbs). In Experiment 3, we carried out an analysis of 340 word endings and found clear orthographic correlates of both grammatical category and lexical stress in word endings. In Experiment 4, we demonstrated that readers are sensitive to these cues in their processing of nonwords during two tasks: sentence construction and stress assignment. We discuss the implications of these findings with regard to psycholinguistic models of single-word reading.     

Multichannel fNIRS assessment of overt and covert confrontation naming

Confrontation naming tasks assess cognitive processes involved in the main stage of word production. However, in fMRI, the occurrence of movement artifacts necessitates the use of covert paradigms, which has limited clinical applications. Thus, we explored the feasibility of adopting multichannel functional near-infrared spectroscopy (fNIRS) to assess language function during covert and overt naming tasks. Thirty right-handed, healthy adult volunteers underwent both naming tasks and cortical hemodynamics measurement using fNIRS. The overt naming task recruited the classical left-hemisphere language areas (left inferior frontal, superior and middle temporal, precentral, and postcentral gyri) exemplified by an increase in the oxy-Hb signal. Activations were bilateral in the middle and superior temporal gyri. However, the covert naming task recruited activation only in the left-middle temporal gyrus. The activation patterns reflected a major part of the functional network for overt word production, suggesting the clinical importance of fNIRS in the diagnosis of aphasic patients.     

Homotopic language reorganization in the right hemisphere after early left hemisphere injury

Speech production is inextricably linked to speech perception, yet they are usually investigated in isolation. In this study, we employed a verbal-repetition task to identify the neural substrates of speech processing with two ends active simultaneously using functional MRI. Subjects verbally repeated auditory stimuli containing an ambiguous vowel sound that could be perceived as either a word or a pseudoword depending on the interpretation of the vowel. We found verbal repetition commonly activated the audition-articulation interface bilaterally at Sylvian fissures and superior temporal sulci. Contrasting word-versus-pseudoword trials revealed neural activities unique to word repetition in the left posterior middle temporal areas and activities unique to pseudoword repetition in the left inferior frontal gyrus. These findings imply that the tasks are carried out using different speech codes: an articulation-based code of pseudowords and an acoustic-phonetic code of words. It also supports the dual-stream model and imitative learning of vocabulary.     

The effects of morphology on the processing of compound words: Evidence from naming,lexical decisions and eye fixations

The use of lexemes during the recognition of spatially unified familiar English compounds was examined in naming, lexical decision and sentence‐reading tasks by manipulating beginning and ending lexeme frequencies while controlling overall compound frequencies. All tasks revealed robust ending lexeme frequency effects, with compound processing being more effective when the ending lexeme was a high‐frequency word. Beginning lexeme frequency effects were more elusive and dependent on task demands. Eye movements, recorded during sentence reading, also indicated that the effects of ending lexemes occurred after the first fixation during compound viewing. Together, the results suggest either that the ending lexeme is used as an access code to locate the meaning of the full compound word or that its meaning is coactive with the meaning of the full compound.     

Single-word predictions of upcoming language during comprehension: Evidence from the cumulative semantic interference task

Comprehenders predict upcoming speech and text on the basis of linguistic input. How many predictions do comprehenders make for an upcoming word? If a listener strongly expects to hear the word “sock”, is the word “shirt” partially expected as well, is it actively inhibited, or is it ignored? The present research addressed these questions by measuring the “downstream” effects of prediction on the processing of subsequently presented stimuli using the cumulative semantic interference paradigm. In three experiments, subjects named pictures (sock) that were presented either in isolation or after strongly constraining sentence frames (“After doing his laundry, Mark always seemed to be missing one …”). Naming sock slowed the subsequent naming of the picture shirt – the standard cumulative semantic interference effect. However, although picture naming was much faster after sentence frames, the interference effect was not modulated by the context (bare vs. sentence) in which either picture was presented. According to the only model of cumulative semantic interference that can account for such a pattern of data, this indicates that comprehenders pre-activated and maintained the pre-activation of best sentence completions (sock) but did not maintain the pre-activation of less likely completions (shirt). Thus, comprehenders predicted only the most probable completion for each sentence.     

Neural enhancement and attenuation induced by repetitive recall

Learning is the process of accumulating information. Repetition can make the process of retrieving information more efficient. The mechanisms by which repetition facilitates the retrieval process, however, are not yet clear. Here, we used event-related functional magnetic resonance imaging to investigate the effects of repetition on cued recall. In this study, participants were asked to encode visually presented semantically unrelated word pairs. The word presented on the left side served as the cue, and the word presented on the right side was the target. In the first test phase, participants were presented with the cue and asked to recall the associated word (target) from the study phase. The second test phase was performed 20 min later using the same method. Participants responded orally during the interval between image acquisitions, and no feedback was provided. Neural activity for identical stimuli and responses across the two tests were compared. As compared with the first test phase, the right dorsolateral prefrontal, bilateral inferior parietal, and precuneus regions showed greater activity and the left inferior frontal areas showed reduced activity during the second test phase. These shifts in neural activity that occurred with repetition may reflect the dynamics of the retrieval process.