Influence of task load on training-induced functional plasticity of the brain using fMRI

Abstract

The brain is very flexible and easily changed by diverse factors, such as new experience, external stimuli, sensory deprivation, diseases, and even by normal aging. This ability is called as “plasticity” of the brain and it is closely related to development, learning, or degeneration. Previous research has shown that activation of the brain depends on the characteristics of task which is being carried out by a subject. However, none of them dealt with the plasticity of the brain based on the characteristics of task. I hypothesized that task load would influence the functional plasticity of the brain, in other words, induced change in brain activation during certain task would be dependent on the load of the task itself, thus induced change in the brain activation might vary with a load of task and be different even within one task. For the task, I tested the influences of variability, required power, and complexity of task, respectively. I used Braille reading for variability, hand grasping for required power, and chopsticks handling and fingers tapping for complexity. For variability, reading Braille of three Korean vowels and that of nine Korean vowels were compared. However, these tasks induced similar pattern of the brain activation before and after learning Braille and practicing for sensing Braille with their left index finger tip. Also, change in the brain activation while reading Braille of three vowels following training was similar to that of nine vowels. Commonly, left hemisphere was more activated after training, and this might be related to acquisition of ability to percept Braille as a language. With the grasping task, the brain activations with 10% and 35% of full power were compared, and there was a difference between two sessions both before and after training, respectively. Interestingly, changing pattern with 10% power following training was opposite of that with 35% power. During grasping of 10% power, left hemisphere was more activated a...