I found this extremely interesting article dated December 2000. Brain Research Implications for Second Language Learning
If you don't feel like reading it or just want to know what I found interesting about it, please read the following quotes from the article.
"Language learning is a natural phenomenon; it occurs even without intervention. "
"The studies discussed below reveal the incredible neural flexibility of the developing (and aging) brain."
"it is the input that determines the function of specific areas of the brain "
"the cortical map can change even in adulthood in response to enriched environmental or learning experiences."
"Learning by the brain is about making connections within the brain and between the brain and the outside world."
"Now, there is direct evidence that when learning occurs, neuro-chemical communication between neurons is facilitated, and less input is required to activate established connections over time."
"For example, exposure to unfamiliar speech sounds is initially registered by the brain as undifferentiated neural activity. Neural activity is diffuse, because the brain has not learned the acoustic patterns that distinguish one sound from another. As exposure continues, the listener (and the brain) learns to differentiate among different sounds and even among short sequences of sounds that correspond to words or parts of words. Neural connections that reflect this learning process are formed in the auditory (temporal) cortex of the left hemisphere for most individuals. With further exposure, both the simple and complex circuits (corresponding to simple sounds and sequences of sounds) are activated at virtually the same time and more easily."
"At the same time that the auditory circuit for the word doggie is activated, the visual circuit associated with the sight of a dog is also activated. Simultaneous activation of circuits in different areas of the brain is called parallel processing.
In early stages of learning, neural circuits are activated piecemeal, incompletely, and weakly. It is like getting a glimpse of a partially exposed and very blurry photo. With more experience, practice, and exposure, the picture becomes clearer and more detailed. As exposure is repeated, less input is needed to activate the entire network. With time, activation and recognition are relatively automatic, and the learner can direct her attention to other parts of the task. This also explains why learning takes time. Time is needed to establish new neural networks and connections between networks."