Random Noise Stimulation Improves Neuroplasticity in Perceptual Learning

Even after reading this 3 times I don't understand, someone needs to tell researchers they need to put their writings into a useful understandable relation to a therapy. Noise here does not refer to sound.
http://www.jneurosci.org/content/31/43/15416.abstract

Abstract
Perceptual learning is considered a manifestation of neural plasticity in the human brain. We investigated brain plasticity mechanisms in a learning task using noninvasive transcranial electrical stimulation (tES). We hypothesized that different types of tES would have varying actions on the nervous system, which would result in different efficacies of neural plasticity modulation. Thus, the principal goal of the present study was to verify the possibility of inducing differential plasticity effects using two tES approaches [i.e., direct current stimulation (tDCS) and random noise stimulation (tRNS)] during the execution of a visual perceptual learning task.