• amblyopia
• cortical plasticity
• visual perceptual learning
• voluntary physical exercise

With an incidence of 1-5% in the worldwide population, amblyopia is the most prevalent one-eye visual impairment. This neurodevelopmental disorder arises from abnormal visual experience early in life, a condition that is in turn due to several causes such as congenital cataract, strabismus, unequal refractive errors or sensory deprivation. Amblyopia is currently considered an untreatable disease after the closure of the critical period for visual plasticity. The occlusion therapy (temporary exclusion of the healthy eye from visual experience by means of an eye patch), the main treatment for centuries, can indeed completely reverse amblyopia only when performed during early postnatal development, but later it shows lower efficiency. In adults, this type of therapy is considered ineffective due to the dramatic decline in visual cortex plasticity following the transition from youth to adulthood. The transition to the mature stage is accompanied by the maturation of different plasticity-limiting factors commonly known as “brakes”. This classic view considers the adult brain a change-resistant structure, with major rewiring of synaptic connections being a distinctive property of the developing nervous system. Nevertheless, an increasing number of studies show that high levels of residual cortical plasticity can be unfolded in the adult brain, when plasticity-limiting brakes are removed.
During my internship, I investigated whether two non-invasive active training procedures, i.e. voluntary physical exercise and perceptual learning, can boost plasticity in adult amblyopic rats. The impact of these procedures on the adult brain was measured using both electrophysiological (visual evoked potentials) and behavioral (Prusky water maze and visual cliff task) methods. Given that physical exercise changes the activation of distinct sub-classes of GABAergic interneurons decreasing intracortical inhibition in the visual cortex, I also started to evaluate if similar cellular mechanisms may underlie the beneficial effects promoted by voluntary physical exercise in the adult brain.