More and more detailed studies are being done to analyze the beneficial effects of meditation on our brains. We often neglect to be aware that we are changing our brains every single day of our lives with the activities we choose. As media and cellphones become larger parts of our lives we also see higher rates of anxiety and depression. Studies such as this one done by Japanese researchers on Zen meditation show the counter to many of these states.
Researchers here recruited novice Zen meditators and analyzed changes in the prefrontal cortex (involved with attention). The study showed significant changes in blood flow/activity to the prefrontal cortex during meditation. They also used EEG scans which showed changes in serotonin levels in the brain (linked to positive mood).
It is clear from this and many other studies that meditation (even in novice meditators) is linked to improvements in mood and the ability to focus the mind.