Cognitive processing of orientation discrimination in anisometropic amblyopia

Abstract

Cognition is very important in our daily life. However, amblyopia has abnormal visual cognition. Physiological changes of the brain during processes of cognition could be reflected with ERPs. So the purpose of this study was to investigate the speed and the capacity of resource allocation in visual cognitive processing in orientation discrimination task during monocular and binocular viewing conditions of amblyopia and normal control as well as the corresponding eyes of the two groups with ERPs. We also sought to investigate whether the speed and the capacity of resource allocation in visual cognitive processing vary with target stimuli at different spatial frequencies (3, 6 and 9 cpd) in amblyopia and normal control as well as between the corresponding eyes of the two groups. Fifteen mild to moderate anisometropic amblyopes and ten normal controls were recruited. Three-stimulus oddball paradigms of three different spatial frequency orientation discrimination tasks were used in monocular and binocular conditions in amblyopes and normal controls to elicit event-related potentials (ERPs). Accuracy (ACC), reaction time (RT), the latency of novelty P300 and P3b, and the amplitude of novelty P300 and P3b were measured. Results showed that RT was longer in the amblyopic eye than in both eyes of amblyopia and non-dominant eye in control. Novelty P300 amplitude was largest in the amblyopic eye, followed by the fellow eye, and smallest in both eyes of amblyopia. Novelty P300 amplitude was larger in the amblyopic eye than non-dominant eye and was larger in fellow eye than dominant eye. P3b latency was longer in the amblyopic eye than in the fellow eye, both eyes of amblyopia and non-dominant eye of control. P3b latency was not associated with RT in amblyopia. Neural responses of the amblyopic eye are abnormal at the middle and late stages of cognitive processing, indicating that the amblyopic eye needs to spend more time or integrate more resources to process the same visual task. Fellow eye and both eyes in amblyopia are slightly different from the dominant eye and both eyes in normal control at the middle and late stages of cognitive processing. Meanwhile, abnormal extents of amblyopic eye do not vary with three different spatial frequencies used in our study.

Psychophysical Reverse Correlation Revealed Broader Orientation Tuning and Prolonged Reaction Time in Amblyopia

“…The AE showed a significantly longer RT than the NE(DE), which is consistent with previous works involving psychophysics 85 – 87 or EEG measurement. 88 The temporal response curve had a flat region that followed the hump, where the stimulus had no influence on the response (see Fig. 6 a, Fig.…”

Management of Abnormal Visual Developments

“…Wang has concluded that both the amblyopic eye and fellow eye exhibiting the longer latency of P3b components as well as the larger amplitude of novelty P300 and P3b. The above researches demonstrate abnormal neural responses of the amblyopic eye at the middle and late stages of cognitive processing, indicating that the amblyopic eye needs to take more time or integrate more resources to process the same visual task [85].…”

Conceptualización integral de la ambliopía

“…Desde el punto de vista de la percepción, la mayoría de los autores concuerda con que la ambliopía se da cuando hay una discordancia entre los estímulos percibidos por cada ojo (10). Aún se mantienen reminicencias de la primitiva definición de Von Graefe, pues en la consulta clínica optométrica no se suelen apreciar causas o alteraciones físicas (11)(12)(13), y pocas veces se toma en cuenta el nivel de sensibilidad al contraste, lo cual ha demostrado también que se ve alterado (4). A esto se le suele agregar que la habilitación visual mediante los métodos ópticos tradicionales resulta insuficiente (14), pero que con procedimientos terapéuticos adecuados, como el parchado, la penalización o el aprendizaje visuoperceptual puede ser reversible (3).…”

“…Se acepta, cada vez más, que este trastorno afecta los procesos perceptuales y multisensoriales de alto nivel (21). Es decir, aunque no sean obvias las causas orgánicas, se entiende que el neurodesarrollo y la neuroestructura se ven alteradas (22). Los circuitos neuronales se encuentran distorsionados (23), e incluso esto se toma como uno de los procesos que dan inicio a la ambliopía, la inhibición de las vías visuales del ojo ambliope por parte del ojo dominante, con la consecuente alteración del cuerpo geniculado lateral (CGL) y de la corteza occipital (24).…”