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Children with ADHD show significant deficits in response inhibition. A leading hypothesis suggests prefrontal hypoactivation as a possible cause, though, there is conflicting evidence. We tested the hypoactivation hypothesis by analyzing the response inhibition process within the oculomotor system. Twenty-two children diagnosed with ADHD and twenty control (CTRL) children performed the antisaccade task while undergoing an fMRI study with concurrent eye tracking. This task included a preparatory stage that cued a prosaccade (toward a stimuli) or an antisaccade (away from a stimuli) without an actual presentation of a peripheral target. This allowed testing inhibitory control without the confounding activation from an actual response. The ADHD group showed longer reaction times and more antisaccade direction errors. While both groups showed activations in saccade network areas, the ADHD showed significant hyperactivation in the dorsolateral prefrontal cortex during the preparatory stage. No other areas in the saccade network had significant activation differences between groups. Further ADHD group analysis OFF and ON stimulant medication did not show drug-related activation differences. However, they showed a significant correlation between the difference in OFF/ON preparatory activation in the precuneus, and a decrease in the number of antisaccade errors. These results do not support the hypoactivity hypothesis as an inhibitory control deficit general explanation, but instead suggest less efficiency during the inhibitory period of the antisaccade task in children. Our findings contrast with previous results in ADHD adults showing decreased preparatory antisaccade activity, suggesting a significant age-dependent maturation effect associated to the inhibitory response in the oculomotor system.

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El Trastorno por Déficit de Atención con Hiperactividad (TDAH) está relacionado con dificultades a nivel de control ejecutivo. Nuevas formas de explorar este constructo contribuyen a la precisión diagnóstica, disminuir la prevalencia y la construcción de un consenso objetivo sobre los criterios del TDAH. El objetivo fue establecer las diferencias en el control ejecutivo de un grupo de niños con TDAH (N=22), con respecto al grupo control (N=15), de ambos géneros y de entre 7 y 12 años de edad, escolarizados de la ciudad de Medellín, Colombia. Se implementaron tres parámetros oculares: fijaciones, antisacadas y prosacadas, los cuales fueron registrados continuamente en un equipo de rastreo visual (Tobii T120). Los resultados indicaron un menor tiempo para el grupo con TDAH en fijaciones oculares (p<,001) que miden control de la interferencia. Un mayor número de errores de dirección en el parámetro antisacadas relacionados con el control inhibitorio. Respecto a las prosacadas, que miden la capacidad para iniciar una respuesta motora, no se encontraron diferencias significativas. Se concluyó que la población con TDAH presenta alteración en el control ejecutivo al utilizar el paradigma de rastreo ocular. Se propusieron, además, los movimientos oculares como posible marcador biológico para detectar una población en riesgo de padecer dicho trastorno.

Attention Deficit Hyperactivity Disorder (ADHD) is related to difficulties at the level of the executive control. New ways of exploring this construct contribute to diagnostic accuracy, decrease the prevalence and build an objective consensus on ADHD criteria. The aim of the study was to establish the differences in the executive control of a group of children with ADHD (N=22), with respect to the control group (N=15), of both genders and between 7 and 12 years old, attending school in the city of Medellin, Colombia. Three ocular parameters were implemented: fixings, antisaccade, and prosaccades, which were recorded continuously in a visual tracking equipment (Tobii T120). The results indicated a shorter time for the group with ADHD in ocular fixations (p<0.001) that measure interference control. A greater number of address errors in the antisaccade parameter related to inhibitory control. Regarding the prosaccades, which measure the capacity to initiate a motor response, no significant differences were found. It was concluded that the population with ADHD presents alteration in the executive control when using the eye tracking paradigm. Eye movements were also proposed as a possible biological marker to detect a population at risk of suffering from this disorder.

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Voluntary gaze control allows people to direct their attention toward selected targets while avoiding distractors. Failure in this ability could be related to dysfunctions in the neural circuits underlying executive functions. Interestingly, recent evidence suggests that factors such as years of schooling and literacy may positively influence goal-directed behavior and inhibitory control. However, we do not yet know whether these factors also have a significant impact on the inhibitory control of oculomotor responses. Using pro- and antisaccadic tasks to assess the behavioral responses of healthy adults, we tested the contribution of years of schooling and reading proficiency to their oculomotor control, while simultaneously analyzing the effects of other individual characteristics related to demographic, cognitive and motor profiles. This approach allowed us to test the hypothesis that schooling factors are closely related to oculomotor performance. Indeed, a regression analysis revealed important contributions of reading speed and intellectual functioning to the choices on both pro- and antisaccadic tasks, while years of schooling, age and block sequence emerged as important predictors of the kinematic properties of eye movements on antisaccadic tasks. Thus, our findings show that years of schooling and reading speed had a strong predictive influence on the oculomotor measures, although age and order of presentation also influenced saccadic performance, as previously reported. Unexpectedly, we found that an indirect measure of intellectual ability also proved to be a good predictor of the control of saccadic movements. The methods and findings of this study will be useful for identifying and breaking down the cognitive and educational components involved in assessing voluntary and automatic responses.

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Analysis of eye movement patterns during tracking tasks represents a potential way to identify differences in the cognitive processing and motor mechanisms underlying reading in dyslexic children before the occurrence of school failure. The current study aimed to evaluate the pattern of eye movements in antisaccades, predictive saccades and visually guided saccades in typical readers and readers with developmental dyslexia. The study included 30 children (age M = 11; SD = 1.67), 15 diagnosed with developmental dyslexia (DG) and 15 regular readers (CG), matched by age, gender and school grade. Cognitive assessment was performed prior to the eye-tracking task during which both eyes were registered using the Tobii® 1750 eye-tracking device. The results demonstrated a lower correct antisaccades rate in dyslexic children compared to the controls (p < 0.001, DG = 25%, CC = 37%). Dyslexic children also made fewer saccades in predictive latency (p < 0.001, DG = 34%, CG = 46%, predictive latency within -300-120 ms with target as 0 point). No between-group difference was found for visually guided saccades. In this task, both groups showed shorter latency for right-side targets. The results indicated altered oculomotor behavior in dyslexic children, which has been reported in previous studies. We extend these findings by demonstrating impaired implicit learning of target's time/position patterns in dyslexic children.

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Diversos aspectos do exame neurológico envolvem conhecimentos oriundos de especialidades afins. Os objetivos principais deste artigo são: tornar manifesto ao exame à beira-do-leito, três tipos de movimento ocular considerados do domínio da neuro-oftalmologia e da neuro-otologia - sacadas, anti-sacadas e perseguição lenta - mas que devem fazer parte do exame neurológico de rotina, além de ressaltar as muitas mazelas relacionadas às suas alterações.

Several parts of the neurological exam utilize knowledge derived from related specialties. This article aims to unveil three ocular movements usually observed in the neuro-ophthalmological and neuro-otological s which can be perfectly used to enhance the routine neurological bedside examination, also uncovering the numerous illnesses related to these ocular movements: saccade, antissacade, and smooth pursuit.

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