Electrophysiological correlates of language processing in schizotypal personality disorder.
(25/3485)
OBJECTIVE: This study examined whether the electrophysiological correlates of language processing found previously to be abnormal in schizophrenia are also abnormal in schizotypal individuals. The authors used the N400 component to evaluate language dysfunction in schizotypal individuals. METHOD: Event-related potentials were recorded in 16 comparison subjects and 17 schizotypal individuals (who met full DSM-III-R criteria) to sentences presented both visually and aurally; half of the sentences ended with an expected word completion (congruent condition), and the other half ended with an unexpected word completion (incongruent condition). RESULTS: In the congruent condition, the N400 amplitude was more negative in individuals with schizotypal personality disorder than in comparison subjects in both the visual and auditory modalities. In addition, in the visual modality, the N400 latency was prolonged in the individuals with schizotypal personality disorder. CONCLUSIONS: The N400 was found to be abnormal in the individuals with schizotypal personality disorder relative to comparison subjects. The abnormality was similar to the abnormality the authors' laboratory reported earlier in schizophrenic subjects, in which the N400 amplitude was found to be more negative in both congruent and incongruent sentence completions. The N400 abnormality is consistent with the inefficient use of context. (+info)
Processing of visually presented sentences in Mandarin and English studied with fMRI.
(26/3485)
Comprehension of visually presented sentences in fluent bilinguals was studied with functional magnetic resonance imaging (fMRI) using a set of conceptually similar sentences in two orthographically and phonologically distinct languages, Mandarin and English. Responses were monitored during scanning. Sentence comprehension in each language was compared to fixation in nine subjects and Tamil-like pseudo-word strings in five subjects. Spatially congruent activations in the prefrontal, temporal, and superior parietal regions and in the anterior supplementary motor area were observed for both languages and in both experiments at the individual and group levels of analysis. Proficient bilinguals exposed to both languages early in life utilize common neuroanatomical regions during the conceptual and syntactic processing of written language irrespective of their differences in surface features. (+info)
Basal forebrain amnesia: does the nucleus accumbens contribute to human memory?
(27/3485)
OBJECTIVE: To analyse amnesia caused by basal forebrain lesions. METHODS: A single case study of a patient with amnesia after bleeding into the anterior portion of the left basal ganglia. Neuropsychological examination included tests of attention, executive function, working memory, recall, and recognition of verbal and non-verbal material, and recall from remote semantic and autobiographical memory. The patient's MRI and those of other published cases of basal forebrain amnesia were reviewed to specify which structures within the basal forebrain are crucial for amnesia. RESULTS: Attention and executive function were largely intact. There was anterograde amnesia for verbal material which affected free recall and recognition. With both modes of testing the patient produced many false positive responses and intrusions when lists of unrelated words had been memorised. However, he confabulated neither on story recall nor in day to day memory, nor in recall from remote memory. The lesion affected mainly the nucleus accumbens, but encroached on the inferior limb of the capsula interna and the most ventral portion of the nucleus caudatus and globus pallidus, and there was evidence of some atrophy of the head of the caudate nucleus. The lesion spared the nucleus basalis Meynert, the diagnonal band, and the septum, which are the sites of cholinergic cell concentrations. CONCLUSIONS: It seems unlikely that false positive responses were caused by insufficient strategic control of memory retrieval. This speaks against a major role of the capsular lesion which might disconnect the prefrontal cortex from the thalamus. It is proposed that the lesion of the nucleus accumbens caused amnesia. (+info)
Are Latinos less satisfied with communication by health care providers?
(28/3485)
OBJECTIVE: To examine associations of patient ratings of communication by health care providers with patient language (English vs Spanish) and ethnicity (Latino vs white). METHODS: A random sample of patients receiving medical care from a physician group association concentrated on the West Coast was studied. A total of 7,093 English and Spanish language questionnaires were returned for an overall response rate of 59%. Five questions asking patients to rate communication by their health care providers were examined in this study. All five questions were administered with a 7-point response scale. MAIN RESULTS: We estimated the associations of satisfaction ratings with language (English vs Spanish) and ethnicity (white vs Latino) using ordinal logistic models, controlling for age and gender. Latinos responding in Spanish (Latino/Spanish) were significantly more dissatisfied compared with Latinos responding in English (Latino/English) and non-Latino whites responding in English (white) when asked about: (1) the medical staff listened to what they say (29% vs 17% vs 13% rated this "very poor," "poor," or "fair"; p <.01); (2) answers to their questions (27% vs 16% vs 12%; p <.01); (3) explanations about prescribed medications (22% vs 19% vs 14%; p <.01); (4) explanations about medical procedures and test results (36% vs 21% vs 17%; p <.01); and (5) reassurance and support from their doctors and the office staff (37% vs 23% vs 18%; p <.01). CONCLUSION: This study documents that Latino/Spanish respondents are significantly more dissatisfied with provider communication than Latino/English and white respondents. These results suggest Spanish-speaking Latinos may be at increased risk of lower quality of care and poor health outcomes. Efforts to improve the quality of communication with Spanish-speaking Latino patients in outpatient health care settings are needed. (+info)
Combined use of biallelic and microsatellite Y-chromosome polymorphisms to infer affinities among African populations.
(29/3485)
To define Y-chromosome haplotypes, we studied seven biallelic polymorphic sites. We combined data with those from four dinucleotide-repeat polymorphisms, to establish Y-chromosome compound superhaplotypes. Eight biallelic haplotypes that matched the dendrogram proposed by other investigators were identified in 762 Y chromosomes from 25 African populations. For each biallelic site, coalescence time of lineages carrying the derived allele was estimated and compared with previous estimates. The "ancestral" haplotype (haplotype 1A) was observed among Ethiopians, "Khoisan" (!Kung and Khwe), and populations from northern Cameroon. Microsatellite distributions within this haplotype showed that the Khoisan haplotypes 1A are widely divergent from those of the other two groups. Populations from northern Africa and northern Cameroon share a haplotype (i.e., 1C), which is not observed in other African populations but represents a major Eurasian cluster. Haplotypes 1C of northern Cameroon are clearly distinct from those of Europe, whereas haplotypes 1C of northern African are well intermingled with those of the other two groups. Apportionment of diversity for the Y-chromosomal biallelic haplotypes was calculated after populations were clustered into different configurations. Despite some correspondence between language affiliation and genetic similarity, geographic proximity seems to be a better predictor of genetic affinity. (+info)
Preserved performance by cerebellar patients on tests of word generation, discrimination learning, and attention.
(30/3485)
Recent theories suggest that the human cerebellum may contribute to the performance of cognitive tasks. We tested a group of adult patients with cerebellar damage attributable to stroke, tumor, or atrophy on four experiments involving verbal learning or attention shifting. In experiment 1, a verb generation task, participants produced semantically related verbs when presented with a list of nouns. With successive blocks of practice responding to the same set of stimuli, both groups, including a subset of cerebellar patients with unilateral right hemisphere lesions, improved their response times. In experiment 2, a verbal discrimination task, participants learned by trial and error to pick the target words from a set of word pairs. When age was taken into account, there were no performance differences between cerebellar patients and control subjects. In experiment 3, measures of spatial attention shifting were obtained under both exogenous and endogenous cueing conditions. Cerebellar patients and control subjects showed similar costs and benefits in both cueing conditions and at all SOAs. In experiment 4, intra- and interdimensional shifts of nonspatial attention were elicited by presenting word cues before the appearance of a target. Performance was substantially similar for cerebellar patients and control subjects. These results are presented as a cautionary note. The experiments failed to provide support for current hypotheses regarding the role of the cerebellum in verbal learning or attention. Alternative interpretations of previous results are discussed. (+info)
Training-induced brain plasticity in aphasia.
(31/3485)
It has long been a matter of debate whether recovery from aphasia after left perisylvian lesions is mediated by the preserved left hemispheric language zones or by the homologous right hemisphere regions. Using PET, we investigated the short-term changes in the cortical network involved in language comprehension during recovery from aphasia. In 12 consecutive measurements of regional cerebral blood flow (rCBF), four patients with Wernicke's aphasia, caused by a posterior left middle cerebral artery infarction, were tested with a language comprehension task. Comprehension was estimated directly after each scan with a modified version of the Token Test. In the interval between the scans, the patients participated in brief, intense language comprehension training. A significant improvement in performance was observed in all patients. We correlated changes in blood flow measured during the language comprehension task with the scores achieved in the Token Test. The regions which best correlated with the training-induced improvement in verbal comprehension were the posterior part of the right superior temporal gyrus and the left precuneus. This study supports the role of the right hemisphere in recovery from aphasia and demonstrates that the improvement in auditory comprehension induced by specific training is associated with functional brain reorganization. (+info)
Linguistic threat activates the human amygdala.
(32/3485)
Studies in animals demonstrate a crucial role for the amygdala in emotional and social behavior, especially as related to fear and aggression. Whereas lesion and functional-imaging studies in humans indicate the amygdala's participation in assessing the significance of nonverbal as well as paralinguistic cues, direct evidence for its role in the emotional processing of linguistic cues is lacking. In this study, we use a modified Stroop task along with a high-sensitivity neuroimaging technique to target the neural substrate engaged specifically when processing linguistic threat. Healthy volunteer subjects were instructed to name the color of words of either threat or neutral valence, presented in different color fonts, while neural activity was measured by using H(2)(15)O positron-emission tomography. Bilateral amygdalar activation was significantly greater during color naming of threat words than during color naming of neutral words. Associated activations were also noted in sensory-evaluative and motor-planning areas of the brain. Thus, our results demonstrate the amygdala's role in the processing of danger elicited by language. In addition, the results reinforce the amygdala's role in the modulation of the perception of, and response to, emotionally salient stimuli. The current study further suggests conservation of phylogenetically older mechanisms of emotional evaluation in the context of more recently evolved linguistic function. (+info)