RESUMEN
PURPOSE: The goals of the study were to further assess contrast sensitivity to (1) investigate the existence of monocular vs. binocular differences; (2) observe possible differences between sample sizes; (3) investigate the effects of test-retest repeatability. METHODS: Contrast sensitivity measurements were obtained by presenting eight horizontal sine-wave gratings (ranging from 0.2 to 20 cycles per degree). A three-up-one-down method was used to obtain thresholds with a criterion of 79.4% correct responses for each spatial frequency. The mean of 12 reversals was used for obtaining thresholds, and the two-alternative forced-choice method was used. Data were recorded in 55 naive observers from 20 to 45 years. All participants were free from identifiable ocular disease and had normal visual acuity. RESULTS: We observed the absence of differences on CSF for both monocular and binocular observers, as well as the absence of differences between large sample sizes. The latter investigation revealed a high degree of repeatability across time (baseline to 6 months later) with the higher test-retest for low and high spatial frequencies. CONCLUSIONS: Our results indicated that spatial contrast sensitivity measurements were little influenced by variables, such as binocular summation, eye dominance, sample size and time using the Metropsis test. The results obtained here have significance for basic and clinical vision science.
Asunto(s)
Sensibilidad de Contraste/fisiología , Programas Informáticos , Procesamiento Espacial/fisiología , Pruebas de Visión/instrumentación , Adulto , Femenino , Humanos , Masculino , Pruebas de Estado Mental y Demencia , Persona de Mediana Edad , Reproducibilidad de los Resultados , Visión Binocular/fisiología , Agudeza Visual/fisiología , Adulto JovenRESUMEN
BACKGROUND: Stroke patients may present severe cognitive impairments, primarily related to executive functions. Transcranial direct current stimulation has shown promising results, with neuromodulatory and neuroplastic effects. This study is a double-blind, sham-controlled clinical trial aiming to compare the long-term effects of stimulation in two different cognitive regions after a stroke. METHODS/DESIGN: Sixty patients who suffer from chronic strokes will be randomized into one of four groups: dorsolateral prefrontal cortex, cingulo-opercular network, motor primary cortex and sham stimulation. Each group will receive transcranial direct current stimulation at an intensity of 2 mA for 20 minutes daily for 10 consecutive days. Patients will be assessed with a Dysexecutive Questionnaire, Semantic Fluency Test, categorical verbal fluency and Go-no go tests, Wechsler Adult Intelligence Scale, Rey Auditory-Verbal Learning Test, Letter Comparison and Pattern Comparison Tasks at baseline and after their tenth stimulation session. Those who achieve clinical improvement with neurostimulation will be invited to receive treatment for 12 months as part of a follow-up study. DISCUSSION: Long-term stimulation could be analyzed in regard to possible adaptive changes on plasticity after structural brain damage and if these changes are different in terms of clinical improvement when applied to two important cognitive centers. TRIALS REGISTRATION: Clinicaltrials.gov, NCT02315807 . 9 December 2014.