RESUMO
Attention directs limited-capacity information processing resources to a subset of available perceptual representations. The mechanisms by which attention selects task-relevant representations for preferential processing are not fully known. Triesman and Gelade's [Triesman, A., Gelade, G., 1980. A feature integration theory of attention. Cognit. Psychol. 12, 97-136.] influential attention model posits that simple features are processed preattentively, in parallel, but that attention is required to serially conjoin multiple features into an object representation. Event-related potentials have provided evidence for this model showing parallel processing of perceptual features in the posterior Selection Negativity (SN) and serial, hierarchic processing of feature conjunctions in the Frontal Selection Positivity (FSP). Most prior studies have been done on conjunctions within one sensory modality while many real-world objects have multimodal features. It is not known if the same neural systems of posterior parallel processing of simple features and frontal serial processing of feature conjunctions seen within a sensory modality also operate on conjunctions between modalities. The current study used ERPs and simultaneously presented auditory and visual stimuli in three task conditions: Attend Auditory (auditory feature determines the target, visual features are irrelevant), Attend Visual (visual features relevant, auditory irrelevant), and Attend Conjunction (target defined by the co-occurrence of an auditory and a visual feature). In the Attend Conjunction condition when the auditory but not the visual feature was a target there was an SN over auditory cortex, when the visual but not auditory stimulus was a target there was an SN over visual cortex, and when both auditory and visual stimuli were targets (i.e. conjunction target) there were SNs over both auditory and visual cortex, indicating parallel processing of the simple features within each modality. In contrast, an FSP was present when either the visual only or both auditory and visual features were targets, but not when only the auditory stimulus was a target, indicating that the conjunction target determination was evaluated serially and hierarchically with visual information taking precedence. This indicates that the detection of a target defined by audio-visual conjunction is achieved via the same mechanism as within a single perceptual modality, through separate, parallel processing of the auditory and visual features and serial processing of the feature conjunction elements, rather than by evaluation of a fused multimodal percept.
Assuntos
Atenção/fisiologia , Percepção Auditiva/fisiologia , Mapeamento Encefálico , Córtex Cerebral/fisiologia , Potenciais Evocados/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica/métodos , Adulto , Análise de Variância , Córtex Cerebral/anatomia & histologia , Eletroencefalografia , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Adulto JovemRESUMO
Disruption of attention is a hallmark symptom of schizophrenia, and event-related potentials have been instrumental in studying this cognitive deficit. Event-related potentials (ERPs) have been used to study attention and its disruption in schizophrenia, with the most common finding of a reduced P300 component in auditory tasks. Some studies have found sparing of the P300 in visual attention, but reduction of an earlier attention-sensitive N2b, suggesting that the N2b may be a more sensitive index of attention disruption in schizophrenia. The current study compared visual and auditory attention using both unimodal and bimodal stimulus presentation in the same participants to examine the impact of schizophrenia on attention at both the early N2b and later P300 stages. Both N2b and P300 showed attention effects, being larger to targets than non-targets in all tasks. The N2b was reduced in the patient group in all tasks except the bimodal attend visual task, while the P300 was not reduced in the patients in any condition. This indicates that early attention, as indexed by the N2b, is differentially impaired in patients with schizophrenia, even when later attention, indexed by the P300, is intact.
Assuntos
Atenção/fisiologia , Percepção Auditiva/fisiologia , Eletroencefalografia , Potenciais Evocados/fisiologia , Esquizofrenia/fisiopatologia , Psicologia do Esquizofrênico , Percepção Visual/fisiologia , Adulto , Idoso , Mapeamento Encefálico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reconhecimento Visual de Modelos/fisiologia , Discriminação da Altura Tonal/fisiologia , Tempo de Reação/fisiologia , Esquizofrenia/diagnósticoRESUMO
Work-related exposures potentially associated with a cluster of brain tumors at a petroleum exploration and extraction research facility were evaluated in a nested case-control study. Fifteen cases were identified in the original cohort and 150 matched controls were selected. Odds ratios (ORs) for occupational exposure to petroleum, radiation, solvents, magnetic fields, and work activities were near or below 1.0. ORs near 1.5 were observed for: working with computers (OR = 1.47; 95% confidence interval [CI] = 0.30-9.35); work-related travel (OR = 1.48; 95% CI = 0.25-5.95), and travel immunizations (OR = 1.62; 95% CI = 0.23-9.45). Higher ORs were observed for work in administrative and marketing buildings and for achieving a master's or higher degree (OR = 2.0, 95% CI = 0.4-10.7). While some ORs above 1.5 were noted, no work-related chemical and physical exposures were significantly associated with the occurrence of brain tumors among employees at this facility.
Assuntos
Neoplasias Encefálicas/epidemiologia , Doenças Profissionais/epidemiologia , Exposição Ocupacional , Petróleo , Pesquisadores , Idoso , Neoplasias Encefálicas/etiologia , Neoplasias Encefálicas/mortalidade , California/epidemiologia , Estudos de Casos e Controles , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Medição de RiscoAssuntos
Anemia/complicações , Transtornos Cognitivos/complicações , Hemoglobinas/análise , Leucemia Mieloide Aguda/complicações , Síndromes Mielodisplásicas/complicações , Adulto , Idoso , Idoso de 80 Anos ou mais , Anemia/sangue , Anemia/patologia , Anemia/fisiopatologia , Biomarcadores/sangue , Transtornos Cognitivos/sangue , Transtornos Cognitivos/patologia , Transtornos Cognitivos/fisiopatologia , Transtornos Cognitivos/psicologia , Estudos Transversais , Feminino , Humanos , Testes de Inteligência , Leucemia Mieloide Aguda/sangue , Leucemia Mieloide Aguda/patologia , Leucemia Mieloide Aguda/fisiopatologia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Síndromes Mielodisplásicas/sangue , Síndromes Mielodisplásicas/patologia , Síndromes Mielodisplásicas/fisiopatologia , Qualidade de Vida , Índice de Gravidade de DoençaRESUMO
BACKGROUND: Prior studies have shown a consistent reduction of the auditory P300 in schizophrenia, while the visual attention findings have been mixed. Both the auditory and visual N2b, an earlier, modality-specific attention index, are reduced in schizophrenia, sometimes despite sparing of the visual P300. Thus there may be a dissociation between the N2b and P300 attention effects in auditory and visual modalities in schizophrenia. METHODS: Thirteen patients and thirteen controls observed symbols appearing on a screen, paired with simultaneous tones. In some blocks subjects responded to one of the symbols, in others to one of the tones. The N2b was predicted to be reduced in the patient group in both auditory and visual attention but the P300 reduced only while attending to tones. RESULTS: Results showed a reduction of the N1 component in the patient group in the auditory condition but not in the visual. There was a reduction of the N2b target-minus-non-target difference wave in the patients in both auditory and visual target conditions. The P300 component was larger overall in the control group in both modalities, but did not show the usual enhancement to auditory targets in the control group. CONCLUSIONS: These findings suggest that the ability to selectively attend to a target in one modality while ignoring the other is compromised in patients with schizophrenia. Perceptual processing appears to be impacted in the auditory modality while remaining intact in the visual. The N2b appears more vulnerable than the P300 in both auditory and visual attention in schizophrenia.
Assuntos
Atenção/fisiologia , Percepção Auditiva/fisiologia , Potenciais Evocados/fisiologia , Esquizofrenia/fisiopatologia , Percepção Visual/fisiologia , Estimulação Acústica/métodos , Adulto , Idoso , Mapeamento Encefálico , Estudos de Casos e Controles , Eletroencefalografia/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Tempo de Reação/fisiologiaRESUMO
Approximately 1800 workers in pipe manufacturing plants in the United States may have been exposed to beta-napthlyamnine between 1970 and 1996. Once the chemical was detected, the contaminated additive in the resin was identified and discontinued. A bladder cancer-screening program was initiated in 1999. An annual two-stage screening program was developed to test for microscopic hematuria (stage one) and cytology (stage two), with a urology referral of positive or suspicious cytology. This paper presents the program methodology, cohort enumeration, recruitment, and enrollment strategies, and screening protocol. Enrollment data from the first 3 years are presented. Annual screening of a cohort of current and former employees is feasible. Original personnel records are often incomplete, making cohort identification important. Personal contact and follow-up are key elements of successful recruitment and retention.
Assuntos
2-Naftilamina , Indústria Química , Doenças Profissionais/prevenção & controle , Neoplasias da Bexiga Urinária/prevenção & controle , Estudos de Coortes , Hematúria/diagnóstico , Hematúria/etiologia , Humanos , Programas de Rastreamento , Neoplasias da Bexiga Urinária/complicações , Urina/citologiaRESUMO
Kidneys are one of the most commonly transplanted solid organs in children. In 2008, 16,067 renal transplants were performed in the United States; of those, 773 were performed on patients under the age of 18 (2009 OPTN/SRTR Annual Report 1999-2008, 2009). The process of renal transplantation can be a long one and children and their families often endure many challenges on the road to the transplant, not to mention the adjustments that lie ahead afterward. For this reason, and because these patients benefit from home health follow-up after their transplant, it is important for home health clinicians to be knowledgeable about the renal transplant process in addition to posttransplant care.
Assuntos
Serviços de Assistência Domiciliar , Transplante de Rim , Adolescente , Criança , Humanos , Adesão à Medicação , Cuidados Pós-Operatórios , Cuidados Pré-OperatóriosRESUMO
Phosphite (H(2)PO(3)(-), Phi) prevents the acclimation of plants and yeast to orthophosphate (Pi, HPO(4)(2-)) deprivation by specifically obstructing the derepression of genes encoding proteins characteristic of their Pi-starvation response. In this study, we report that prolonged (i.e., 3-4 weeks) culture of Brassica napus L. suspension cells in Pi-deficient (-Pi) media leads to programmed cell death (PCD). However, when the B. napus cells were subcultured into -Pi media containing 2 mM Phi, they initiated PCD within 5 days, with 95% cell death observed by day 9. Dying cells exhibited several morphological and biochemical features characteristic of PCD, including protoplast shrinkage, chromatin condensation, and fragmentation of nuclear DNA. Immunoblotting indicated that B. napus cells undergoing PCD upregulated a 30-kDa cysteine endoprotease that is induced during PCD in the inner integument cells of developing B. napus seeds. It is concluded that PCD in B. napus suspension cells is triggered by extended Pi starvation, and that Phi treatment greatly accelerates this process. Our results also infer that the adaptive value of acclimating at the molecular level to Pi-stress is to extend the viability of -Pi B. napus cell cultures by about 3 weeks.