Psychophysical sensitivity to isoluminant chromatic modulation declines at temporal frequencies beyond 4 Hz, whereas chromatically opponent cells of the afferent visual pathway (long- to middle-wavelength (L-M) cone-opponent or short-wavelength (S) cone cells) show responses at much higher temporal frequencies, indicating a central limitation in temporal processing capacity. Here, we sought to localize this limit in cortical retinotopic visual areas. We used fMRI to investigate responses of lateral geniculate nucleus and cortical visual areas in humans to isoluminant chromatic modulation as a function of temporal frequency (2-12 Hz). Our results suggest that L-M cone-opponent and S-cone signals are processed in LGN up to 12 Hz. In all visual areas except MT (middle temporal) and V3a, S-cone responses declined steeply with temporal frequency, implying that psychophysical sensitivity loss to blue-yellow modulation might occur early within these areas. While V1 showed robust L-M responses up to 12 Hz, there was a progressive falloff of responses with temporal frequency as information is transferred from V1 to higher areas (V2, V3, and V4), suggesting that, in humans, temporal limitation in perception of red-green chromatic modulation likely results from limited processing capacity of higher ventral extrastriate areas.
Introduction The hormonal changes that occur during the menstrual cycle and their relationship with hearing problems have been studied. However, they have not been well explained. Objective The objective of our study is to investigate the variation in hearing thresholds in women during the menstrual cycle. Method We conducted a cohort and longitudinal study. It was composed of 30 volunteers, aged 18–39 years old, of which 20 were women during the phases of the menstrual cycle and 10 were men (control group) who underwent audiometry and impedance exams, to correlate the possible audiological changes in each phase of the menstrual cycle. Results There were significant changes in hearing thresholds observed during the menstrual cycle phases in the group of women who used hormonal contraceptives and the group who did not use such contraceptives. Improved hearing thresholds were observed in the late follicular phase in the group who did not use hormonal contraceptives and the hearing thresholds at high frequencies were better. Throughout the menstrual cycle phases, the mean variation was 3.6 db HL between weeks in the group who used hormonal contraceptives and 4.09 db HL in the group who did not use them. Conclusions The present study found that there may be a relationship between hearing changes and hormonal fluctuations during the menstrual cycle based on changes in the hearing thresholds of women. In addition, this study suggests that estrogen has an otoprotective effect on hearing, since the best hearing thresholds were found when estrogen was at its maximum peak.
ResumoIntrodução: As flutuações hormonais que ocorrem normalmente durante o ciclo menstrual podem interferir no sistema auditivo. A alteração mais encontrada neste período é a diminuição da acuidade auditiva, que parece estar mais associada à flutuação dos níveis de estrogênio, quando este se encontra reduzido na fase lútea final do período menstrual. Objetivo: Investigar por meio de uma revisão sistemática a percepção auditiva de mulheres durante as fases do ciclo menstrual. Método: Foi realizada uma busca nas bases de dados eletrônicas, nacionais e internacionais, LILACS, MEDLINE, PubMed e SciELO, *Universidade Federal da Paraíba, João Pessoa, PB, Brasil. ** Universidade Tuiuti do Paraná, Curitiba, PR, Brasil. Contribuição dos autores:CSC, DSS e RTSC: coleta, tabulação, interpretação dos dados e construção do artigo. AKLB e AR: delineamento do estudo e revisão final do artigo. DAHH: análise e interpretação dos resultados. MRDR: delineamento do estudo, orientação e revisão do artigo. através da consulta pelos seguintes descritores: "percepção auditiva" AND "ciclo menstrual", "percepção de fala" AND "ciclo menstrual", "percepção de fala" AND "hormônios" e seus correspondentes na língua inglesa. Resultados: Dos 293 artigos encontrados, foram selecionados apenas 7 artigos, após os critérios de inclusão e exclusão. A caracterização da amostra dos artigos selecionados variou entre 15 a 39 mulheres, com idade variando entre 17 e 46 anos. Na maioria dos artigos, nenhum tipo de procedimento clínico para estimar as fases do ciclo menstrual foi utilizado. Foi observada a realização de testes de percepção auditiva nos sete artigos selecionados, tendo destaque os testes dicóticos. Conclusão: Há necessidade da realização de mais pesquisas sobre o assunto, exigindo-se também maior rigor metodológico na elaboração desses estudos, através de procedimentos clínicos seguros e padronizados para mensuração dos níveis hormonais. E-mail para correspondência:Palavras-chave: Hormônios; Ciclo menstrual; Percepção de fala; Percepção auditiva. AbstractIntroduction: Hormonal fluctuations that normally occur during the menstrual cycle can interfere with the audio system. The change most found in this period is the reduction of auditory acuity, which seems to be more related to fluctuating estrogen levels, when it is reduced in the luteal phase of the menstrual period end. Objective: Investigate through a systematic review hearing in women during the menstrual cycle phases. Method: A search was made in the electronic databases, national and international, LILACS, MEDLINE, PubMed and SciELO, by consulting the following descriptors: "auditory perception" and "menstrual cycle", "speech perception" and "menstrual cycle", "speech perception" and "hormones" and their corresponding in Portuguese. Results: Twenty-two articles were found, but only 7 articles were chosen after the criteria for inclusion and exclusion. The amount of the sample of selected articles ranged between 15 and 39 women, aged between 17 and 46 years old. In most articles, any ...
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