Hello,
We are working on a group speech for a school project and need to reach out to an expert in the field of psychology. We have a few questions about the topic of brain capacity and we would greatly appreciate it if you would take a look at them and get back to us.
Here are our questions:
Does exercise affect how well the brain functions?
Can certain exercises be done to improve brain capacity? If so, what are some examples?
How much information can the brain hold?
Where did the myth of only 10 percent brain capacity come from?
What general methods do you think work best to fix brain injuries?

Thank you!

Today the above email arrived and reflects questions that come up fairly often to me as a memory researcher.  I decided to answer them here on the blog for availability for future reference (I might have actually done this before, at some point I should look and collect similar posts).

General answers:

• Physical exercise probably does not have much immediate impact on brain function other than being fatigued after exercising might very temporarily slow function.  Longer-term, cardio-vascular fitness appears to be important in healthy aging.  Maintaining physical fitness through middle age and late life looks to be very helpful in keeping your brain working well.
• Cognitive exercises also seem to help healthy aging.  It is less clear how well cognitive exercise helps younger people.  Most things that keep you cognitively active result in learning and for younger people and the information learned is probably the most important thing.  Being cognitively active mainly means doing interesting things that make you think.  Staying active when you are older probably helps with something like ‘capacity’ while doing this when you are young makes you smarter in a more direct way.
• The brain appears to have the capacity to hold everything you are capable of learning over the course of your life.  It doesn’t appear to work that way — we forget things a lot — but this is due to problems storing everything permanently more than running out of room to store them.  Storing memories is slower than experiencing things, so a lot of your experiences don’t end up in your long-term memory.
• The brain is made of neurons.  Neurons are electrically active when they are functioning.  You definitely don’t want them all firing at the same time — that would cause a seizure, as in epilepsy.  If the 10% idea has any basis at all, it’s related to about how many neurons could be firing at about the same time.  There is no hidden, reserve unused capacity in your brain.
• The major problem with brain injuries is that neurons don’t grow back.  Almost all treatment and rehabilitation is training new processes to work with the remaining uninjured parts of the brain, and learning to work around the damaged parts.  This can work surprisingly well to recover function, but you can never really recover or replace lost brain tissue, unfortunately.