Pretraining alpha rhythm enhancement by neurofeedback facilitates short-term perceptual learning and improves visual acuity by facilitated consolidation.

Introduction: Learning through perceptual training using the Gabor patch (GP) has attracted attention as a new vision restoration technique for myopia and age-related deterioration of visual acuity (VA). However, the task itself is monotonous and painful and requires numerous training sessions and some time before being effective, which has been a challenge for its widespread application. One effective means of facilitating perceptual learning is the empowerment of EEG alpha rhythm in the sensory cortex before neurofeedback (NF) training; however, there is a lack of evidence for VA. Methods: We investigated whether four 30-min sessions of GP training, conducted over 2 weeks with/without EEG NF to increase alpha power (NF and control group, respectively), can improve vision in myopic subjects. Contrast sensitivity (CS) and VA were measured before and after each GP training. Results: The NF group showed an improvement in CS at the fourth training session, not observed in the control group. In addition, VA improved only in the NF group at the third and fourth training sessions, this appears as a consolidation effect (maintenance of the previous training effect). Participants who produced stronger alpha power during the third training session showed greater VA recovery during the fourth training session. Discussion: These results indicate that enhanced pretraining alpha empowerment strengthens the subsequent consolidation of perceptual learning and that even a short period of GP training can have a positive effect on VA recovery. This simple protocol may facilitate use of a training method to easily recover vision.

Automated grating contrast-sensitivity: The easy test for hidden visual loss in recovered optic neuritis patient.

PURPOSE: Residual visual loss is an important predictor of optic neuritis relapse and progression. This study aimed to investigate the hidden residual visual loss in patients with optic neuritis using automated contrast-sensitivity (CS) function testing. MATERIALS AND METHODS: This cross-sectional study investigated 29 recovered optic neuritis patients (age: 27.69 ± 13.32 years, range: 13-51). Twenty age-matched controls with normal visual acuity (VA, in LogMAR) were recruited, for comparison with patients' VA and CS function after stable recovery from optic neuritis (6 months of follow-up). CS tests used a novel software that displays a single set of Gabor patches (2 cycles per degree at 10° ×10° of visual angle) with contrasts grating from 100% to 0.1%. RESULTS: There were 13 adolescent patients (63.6%: retrobulbar neuritis [RN]; 36.4%: papillitis), 14 adult patients (50%: RN; 42.9%: papillitis), and only 2 older patients (all with neuroretinitis). There was improvement of VA in the patient group at first diagnosis and follow-up (VA initial vs. final: 1.438 ± 1.134 vs. 0.235 ± 0.272, P < 0.001). This VA improvement was similar to control group (P = 0.052). In CS, there were significant differences in patient versus control groups (69.069% ± 70.235% vs. 27.215% ± 25.27%, P = 0.025). Linear regression showed that initial VA and CS function could not predict final VA (P = 0.183 and P = 0.138, respectively). CONCLUSIONS: Patients with optic neuritis showed decreased CS compared to control group which indicated the residual visual loss. Automated CS testing is useful in detecting residual visual loss in patients who recovered from optic neuritis.

The quest for the genuine visual mismatch negativity (vMMN): Event-related potential indications of deviance detection for low-level visual features.

Research shows that the visual system monitors the environment for changes. For example, a left-tilted bar, a deviant, that appears after several presentations of a right-tilted bar, standards, elicits a classic visual mismatch negativity (vMMN): greater negativity for deviants than standards in event-related potentials (ERPs) between 100 and 300 ms after onset of the deviant. The classic vMMN is contributed to by adaptation; it can be distinguished from the genuine vMMN that, through use of control conditions, compares standards and deviants that are equally adapted and physically identical. To determine whether the vMMN follows similar principles to the auditory mismatch negativity (MMN), in two experiments we searched for a genuine vMMN from simple, physiologically plausible stimuli that change in fundamental dimensions: orientation, contrast, phase, and spatial frequency. We carefully controlled for attention and eye movements. We found no evidence for the genuine vMMN, despite adequate statistical power. We conclude that either the genuine vMMN is a rather unstable phenomenon that depends on still-to-be-identified experimental parameters, or it is confined to visual stimuli for which monitoring across time is more natural than monitoring over space, such as for high-level features. We also observed an early deviant-related positivity that we propose might reflect earlier predictive processing.

Detección de la dirección del movimiento global en estudiantes con trastornos ortográficos / Detection of the global movement direction in students with orthographic disorders

Se realizó un estudio descriptivo y prospectivo, desde enero hasta mayo del 2014, a fin de caracterizar la detección de la dirección del movimiento global en alumnos con trastornos ortográficos, para lo cual se empleó el parche de Gabor. Se seleccionaron 2 grupos de estudiantes de 9-11 años; uno con trastornos ortográficos y el otro con buen rendimiento académico, pertenecientes a la Escuela Primaria "Nguyen Van Troi" de Santiago de Cuba. Los resultados indicaron que los niños del primer grupo no realizaban adecuadas inferencias perceptivas de la dirección del movimiento global. No existieron evidencias de que la ventaja global facilitara la detección de la dirección del movimiento; por tanto, cometieron más errores al determinar la trayectoria del movimiento para orientaciones verticales del enrejado, no así para la ubicación horizontal donde mostraron su mejor desempeño.

A descriptive and prospective study was carried out from January to May, 2014, in order to characterize the detection of the global movement direction in students with orthographic disorders, for which the Gabor patch was used. Two groups of 9-11 years students were selected; one with orthographic disorders and the other one with good academic results, belonging to "Nguyen Van Troi" Primary School in Santiago de Cuba. The results indicated that children of the first group didn't carry out appropriate perceptive inferences of the global movement direction. There were no evidences that the global advantage facilitated the detection of the movement direction; therefore, they made more mistakes when determining the trajectory of the movement for vertical orientations of the grating, on the contrary for the horizontal location where they showed their best performance.

Valuable Orientations Capture Attention.

Visual attention has long been known to be drawn to stimuli that are physically salient or congruent with task-specific goals. Several recent studies have shown that attention is also captured by stimuli that are neither salient nor task-relevant, but that are rendered in a color that has previously been associated with reward. We investigated whether another feature dimension-orientation-can be associated with reward via learning and thereby elicit value-driven attentional capture. In a training phase, participants received a monetary reward for identifying the color of Gabor patches exhibiting one of two target orientations. A subsequent test phase in which no reward was delivered required participants to search for Gabor patches exhibiting one of two spatial frequencies (orientation was now irrelevant to the task). Previously rewarded orientations robustly captured attention. We conclude that reward learning can imbue features other than color-in this case, specific orientations-with persistent value.

Categorization of multidimensional stimuli by pigeons.

Six pigeons responded in a visual category learning task in which the stimuli were dimensionally separable Gabor patches that varied in frequency and orientation. We compared performance in two conditions which varied in terms of whether accurate performance required that responding be controlled jointly by frequency and orientation, or selectively by frequency. Results showed that pigeons learned both category tasks, with average overall accuracies of 85.5% and 82% in the joint and selective control conditions, respectively. Although perfect performance was possible, responding for all pigeons fell short of optimality. Model comparison analyses showed that the General Linear Classifier (GLC; Ashby, 1992) provided a better account of responding in the joint control condition than unidimensional models, but a unidimensional model fitted better for the condition that required selective control by frequency. Our results show that pigeons' responding in a visual categorization task can be controlled jointly or selectively by stimulus dimensions, depending on reinforcement contingencies. However, analysis of residuals confirmed that systematic deviations of GLC predictions from the obtained data were present in both conditions, suggesting that an alternative account of responding in multidimensional category learning tasks may be necessary.