Two studies reporting on potential recovery of visual function following monocular deprivation ― the blocking of vision in one eye ― are published in Nature Communications this week.
Karen Montey and Elizabeth Quinlan show that following chronic monocular deprivation in rats, the number of dendritic spines found on neurons in the primary visual cortex in the brain decrease, as well as the strength of synapses between the thalamus and the cortex. They find that dark exposure in adulthood allowed the recovery of dendritic spines density and the strength of the synaptic transmissions. These findings demonstrate that dark exposure in adulthood reactivates forms of synaptic plasticity observed in the juvenile visual cortex.
In a second report, Maria Spolidoro and colleagues show that food restriction in adulthood also allows recovery from monocular deprivation. The authors illustrate this by inducing monocular deprivation and then reducing the calorie intake of rats for one month. After this time they can show that visually evoked responses are restored. They conclude that food restriction can therefore also restore plasticity in adulthood. It is, however, unclear at this stage whether the food restriction regime used in rats would also allow restoration of monocular deprivation in humans or whether this dietary regime would be feasible.
Together these two studies highlight the ability to promote plasticity in the adult brain and have potential implications for recovery from some visual disorders in humans.