“Global” visual training and extent of transfer in amblyopic macaque monkeys

Abstract

Perceptual learning is gaining acceptance as a potential treatment for amblyopia in adults and children beyond the critical period. Many perceptual learning paradigms result in very specific improvement that does not generalize beyond the training stimulus, closely related stimuli, or visual field location. To be of use in amblyopia, a less specific effect is needed. To address this problem, we designed a more general training paradigm intended to effect improvement in visual sensitivity across tasks and domains. We used a "global" visual stimulus, random dot motion direction discrimination with 6 training conditions, and tested for posttraining improvement on a motion detection task and 3 spatial domain tasks (contrast sensitivity, Vernier acuity, Glass pattern detection). Four amblyopic macaques practiced the motion discrimination with their amblyopic eye for at least 20,000 trials. All showed improvement, defined as a change of at least a factor of 2, on the trained task. In addition, all animals showed improvements in sensitivity on at least some of the transfer test conditions, mainly the motion detection task; transfer to the spatial domain was inconsistent but best at fine spatial scales. However, the improvement on the transfer tasks was largely not retained at long-term follow-up. Our generalized training approach is promising for amblyopia treatment, but sustaining improved performance may require additional intervention.

Amblyopia: New molecular/pharmacological and environmental approaches

“…Therefore, there is a continued need to seek novel, faster training approaches. For example, a study in adult amblyopic macaques suggested that implementing a ‘global’ training paradigm may lead to visual improvements that generalize beyond the trained stimulus (Kiorpes & Mangal, 2015). Moreover, training strategies that engage attentional and emotional processes, including movies and action video games, appear in some reports to be particularly successful (reviewed in Levi & Li, 2009, and in Bavelier et al, 2010).…”

The Puzzle of Visual Development: Behavior and Neural Limits

“…Moreover, when studying a disorder, it is important that the behavioral and neural profiles of that disorder are similar between the model species and humans. Macaques naturally develop amblyopia (Kiorpes, 1989;, and the approaches used to model human amblyopia in macaques yield a visual disorder that parallels the human condition both in basic visual function and more complex perceptual losses (Boothe et al, 1985;Kiorpes, 2008Kiorpes, , 2015Kiorpes and Mangal, 2015). …”

The Neurology of Amblyopia: A Further Evaluation of Data from the Eyetronix Flicker Glass Clinical Study

“…Perceptual learning uses repeated exposure to a perceptual task (commonly approximately 3500, but sometimes 20,000 to 35,000 trials) to improve acuity in amblyopia, and lately in infantile nystagmus. A criticism has been lack of transfer, or generalization of gains to behaviors beyond the training stimulus (Kiorpes, 2015), Huurneman, Boonstra, Goossens, 2016a & b). The improved reading symptoms reported here might be deemed surprising by some with familiarity with perceptual learning, especially with no reading-specific training as part of the Eyetronix study.…”