Latência e amplitude do P300 auditivo na doença de Alzheimer: uma revisão sistemática

O P300 desempenha um papel fundamental como método de avaliação e monitoramento das demências, entre elas a doença de Alzheimer. OBJETIVO: Realizar uma busca por artigos que analisaram os valores de latência e amplitude de P300 na doença de Alzheimer. MÉTODOS: Foi realizada uma busca nas seguintes bases de dados: Web of Science, PubMed/Medline, Psyc Info, Biological Abstracts e Scielo. Utilizaram-se as seguintes palavras-chave: speed of information processing, speed of processing, information processing, aged, older, elderly, older people, alzheimer dementia, alzheimer disease, Alzheimer, além de referências cruzadas dos artigos selecionados. RESULTADOS: Foram encontrados oito estudos que preencheram os critérios de inclusão adotados para o presente trabalho. Estes estudos mostraram que existe um consenso em relação ao aumento da latência de P300 de idosos com doença de Alzheimer quando comparados com idosos sem a doença. Porém, verifica-se que, com relação à amplitude de P300, ainda não há um consenso, mas, isso pode estar relacionado às diferentes variáveis metodológicas adotadas nos estudos revisados. CONCLUSÃO: Há necessidade de se padronizar as variáveis envolvidas no método de avaliação do P300 para idosos com doença de Alzheimer, para que seja possível comparar os valores de latência e amplitude de P300 dessa população.

Síndrome da apneia obstrutiva do sono e o potencial auditivo P300

A Síndrome da Apneia Obstrutiva do Sono (SAOS) diminui as capacidades da atenção, memória e concentração, fatores relacionados com a cognição. A análise dos parâmetros do P300 auditivo permitiria inferir disfunção cognitiva. OBJETIVO: Comparar os dados da polissonografia e do P300 auditivo em adultos, roncopatas primários com portadores de SAOS. CASUÍSTICA E MÉTODO: Estudo prospectivo em roncopatas primários (N=12) e em portadores de SAOS (N=54), submetidos à polissonografia definidos pelo índice de apneia e hipopneia (IAH). As variáveis da polissonografia e as do P300 foram comparadas, pelos testes T de Student, exato de Fisher, regressão logística e análise de correlação com nível de significância de 5%. RESULTADOS: O IAH apresentou correlação inversa com a oximetria em ambos os grupos. A prevalência do P300 foi menor no G.SAOS (teste exato de Fisher, p=0,027). A idade dos pacientes não influenciou a prevalência do P300 (análise de regressão; p=0,232). A amplitude do P300 foi menor do G.SAOS (teste T de Student; p=0,003) a latência do P300 foi semelhante em ambos os grupos (teste T de Student; p=0,89). CONCLUSÃO: A redução da amplitude do P300 nos portadores de SAOS sugere disfunção cognitiva induzida por diminuição da memória auditiva.

Effects of Transcranial Magnetic Stimulation on the Cognitive Event-Related Potential P300: A Literature Review

The objective of this study was to perform a systematic review regarding the effects of transcranial magnetic stimulation (TMS) on the cognitive event-related potential P300. A search was performed of the PubMed database, using the keywords "transcranial magnetic stimulation" and "P300." Eight articles were selected and, after analysis of references, one additional article was added to the list. We found the comparison among studies to be difficult, as the information regarding the effects of TMS on P300 is both scarce and heterogeneous with respect to the parameters used in TMS stimulation and the elicitation of P300. However, 7 of 9 studies found positive results. New studies need to be carried out in order to understand the contribution of these variables and others to the alteration in the latency and amplitude of the P300 wave.

Potencial cognitivo P300 em indivíduos com diabetes mellitus

Diabetes Mellitus may lead to alterations in the eyes, kidneys, cranial nerves, peripheral nerves, ears etc. The cognitive function, also, seems to be compromised in subjects presented with Diabetes Mellitus, since the cortical and subcortical structures responsible for this function are hindered in some insulin-dependent patients. The cognitive potential P300 has been used as an objective procedure to assess cerebral cognitive functions. Objective: Analyze the sensitivity of P300 cognitive potential for the detection of alterations on the auditory cortex secondary to Diabetes Mellitus. Study design: transversal cohort. Material and Method: Sixteen diabetic subjects of both genders aged 7 to 71 years, and seventeen non-diabetic individuals at the same age range participated in this study, the evaluation procedures were pure tone audiometry (PTA) and P300 cognitive potential. Glycemia of the group presented with Diabetes was assessed prior to applying the P300. Results: No statistically significant difference was shown for the PTA results. A statically significant difference was observed between groups when analyzing the latency of the P300 component measured in Fz. there was a correlation between glycemia and the latency and amplitude of P300. Conclusion: The investigation of the cognitive potential of P300 is an important procedure for the prevention and early diagnosis of neurological changes in individuals presented with Diabetes Mellitus.

P300 in individuals with sensorineural hearing loss

INTRODUCTION: Behavioral and electrophysiological auditory evaluations contribute to the understanding of the auditory system and of the process of intervention. OBJECTIVE: To study P300 in subjects with severe or profound sensorineural hearing loss. METHODS: This was a descriptive cross-sectional prospective study. It included 29 individuals of both genders with severe or profound sensorineural hearing loss without other type of disorders, aged 11 to 42 years; all were assessed by behavioral audiological evaluation and auditory evoked potentials. RESULTS: A recording of the P3 wave was obtained in 17 individuals, with a mean latency of 326.97 ms and mean amplitude of 3.76 V. There were significant differences in latency in relation to age and in amplitude according to degree of hearing loss. There was a statistically significant association of the P300 results with the degrees of hearing loss (p = 0.04), with the predominant auditory communication channels (p < 0.0001), and with time of hearing loss. CONCLUSIONS: P300 can be recorded in individuals with severe and profound congenital sensorineural hearing loss; it may contribute to the understanding of cortical development and is a good predictor of the early intervention outcome.

Blink reflex: comparison of latency measurements in different human races

Latências do reflexo trigêmino-facial e índices cefalométricos foram analisados em 30 voluntários adultos normais, de 3 diferentes raças, sendo 10 brancos, 10 negros e 10 orientais. Idades variaram de 15 a 59 anos, alturas de 1,6 a 1,8 m e pesos de 60 a 80 kg. Os reflexos trigêmino-faciais foram obtidos por estimulação elétrica unilateral do nervo supra-orbital e captação nos músculos orbicularis oculi, para análise quantitativa de 3 respostas, ipsolateral precoce (R1), ipsolateral tardia (R2i) e contralateral tardia (R2c). Índices cefalométricos foram obtidos multiplicando-se por 100 a razão entre maior diâmetro transverso e maior diâmetro sagital do crânio. As médias dos índices cefalométricos de cada grupo foram compatíveis com as respectivas características raciais. As respostas R1, R2i e R2c não mostraram diferenças de latências estatisticamente significativas entre as 3 diferentes raças analisadas neste estudo.

The central repeat domain 1 of Kaposi's sarcoma-associated herpesvirus (KSHV) latency associated-nuclear antigen 1 (LANA1) prevents cis MHC class I peptide presentation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen 1 mimics Epstein-Barr virus EBNA1 immune evasion through central repeat domain effects on protein processing

Kaposi's sarcoma-associated herpesvirus (KSHV/human herpesvirus 8 [HHV8]) and Epstein-Barr virus (EBV/HHV4) are distantly related gammaherpesviruses causing tumors in humans. KSHV latency-associated nuclear antigen 1 (LANA1) is functionally similar to the EBV nuclear antigen-1 (EBNA1) protein expressed during viral latency, although they have no amino acid similarities. EBNA1 escapes cytotoxic lymphocyte (CTL) antigen processing by inhibiting its own proteosomal degradation and retarding its own synthesis to reduce defective ribosomal product processing. We show here that the LANA1 QED-rich central repeat (CR) region, particularly the CR2CR3 subdomain, also retards LANA1 synthesis and markedly enhances LANA1 stability in vitro and in vivo. LANA1 isoforms have half-lives greater than 24 h, and fusion of the LANA1 CR2CR3 domain to a destabilized heterologous protein markedly decreases protein turnover. Unlike EBNA1, the LANA1 CR2CR3 subdomain retards translation regardless of whether it is fused to the 5′ or 3′ end of a heterologous gene construct. Manipulation of sequence order, orientation, and composition of the CR2 and CR3 subdomains suggests that specific peptide sequences rather than RNA structures are responsible for synthesis retardation. Although mechanistic differences exist between LANA1 and EBNA1, the primary structures of both proteins have evolved to minimize provoking CTL immune responses. Simple strategies to eliminate these viral inhibitory regions may markedly improve vaccine effectiveness by maximizing CTL responses. Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Processamento auditivo comportamental e eletrofisiológico em crianças com Transtorno de Déficit de Atenção com Hiperatividade (TDAH)

Pós-graduação em Fonoaudiologia - FFC

Efeito da variação de frequência e duração do estímulo no registro do P300 e MMN

Pós-graduação em Fonoaudiologia - FFC

Processamento auditivo em trabalhadores expostos a ruído e inseticida: testes de ordenação temporal e P300

Pós-graduação em Fonoaudiologia - FFC

Long latency auditory evoked potential in Asperger Syndrome: two case studies

Introduction: Auditory Late Responses (ALR) assess central auditory processing by neuro electric activity of the auditory pathway and analyse the activities involved in cortical abilities of discrimination, attention and integration of the brain. Individuals withAsperger Syndrome experience changes in these skills, so it is important to research these potential this population. The objective of this paper was to describe the auditory late responses of two patients with Asperger Syndrome. Methods: The study included two male patients with Asperger Syndrome, of 7 and 12 years of age, treated in a study centre. The patients did not present any auditory complaint detected by an amnesis. The external auditory canal was inspected and audiological and auditory late responses assessed. After evaluation the components P2, N2 and P3 were analysed. Results: In both patients, the latency of the components P2, N2 and P3 were elongated in both ears. Regarding the amplitude of the P2 component, reduced values were found for the left ear of patient 1 and the right ear of patient 2. The N2 amplitude was reduced for both ears of patient 1 and only the right ear of patient 2. The two patients showed a decrease in the amplitude of the P3 only in the right ear. Conclusion:This study concludes that there were changes in the ALR results in both patients with Asperger Syndrome, suggesting alteration of the auditory function at the cortex level.

Origin and function of short-latency inputs to the neural substrates underlying the acoustic startle reflex

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Associação entre o potencial evocado auditivo de longa latência e os índices lineares da variabilidade da frequência cardíaca em repouso

Pós-graduação em Fonoaudiologia - FFC