Music can have incredibly powerful effects on the human brain.
This has been known for quite some time, but exactly how it affects the mind has been largely unknown until fairly recently. Listening to music is definitely beneficial for your mind, as it requires your brain to analyze different moving parts and assemble them in order for you to truly understand what is happening.
An even greater thing happens, though, when you play an instrument. Each and every time someone plays an instrument, their gray matter goes berserk in the best way. By observing the brains of people who play musical instruments while they play them, scientists found that nearly every area of their minds were engaged while they played. This is because it requires the use of both hemispheres of the brain — the left side, because playing an instrument requires refined skill and some mathematics, and the right side because you are being creative.
As the video below explains, the most active parts of the mind while playing an instrument are the visual, auditory, and motor cortices, and playing an instrument is essentially like sending your brain to the gym. Because of this, people who play instruments generally have better visual, auditory, and motor skills, all of which come together to enhance their overall brain activity.
So dust off that guitar in the back of your closet and get to work flexing your brain!