How the Brain Works: Test Your Medical IQ

It's a common myth that we only use 10% of our brains. Evidence shows humans use 100% of our brains. We may not use all of our brain at any given moment, but most of our brain is active most of the time, and over a day 100% of it gets used.

The so-called "Mozart effect" is the myth that playing classical music for babies while in utero will help increase intelligence or boost IQ. However, studies have debunked this myth. The best way to increase intelligence in terms of music is to give a young child a musical instrument to learn. A 1997 UCLA study of 25,000 students found that those who studied music tested higher on the SATs and reading proficiency exams than students not exposed to musical pursuits.

Even though people are typically considered adults at age 18, brain development continues until our 20s. The prefrontal cortex, the part of the brain that keeps impulses in check, allows you to work toward goals, and helps evaluate consequences is not fully developed until about age 25.

The idea that people are either "left-brained" or "right-brained" is a myth. The myth states that people who are logical and skilled in math or languages are left-brained, while people who are artistic and creative are right-brained came from studies of people who had the hemispheres of their brain disconnected from one another as a last resort treatment for severe epilepsy. While the two hemispheres of the brain function differently, in healthy people they are connected and each side communicates with the other.

In addition to dreaming, the brain is very busy while you sleep. It helps improve your memory by moving newly learned information or skills to regions of the brain that store long-term memories, clears out waste products that build up during the day, and processes information to make connections that help us with decision-making or creativity.

We've all heard of so-called visual learners, or verbal learners, or those who like to learn with their hands. For a long time it was believed that if people learned in their preferred learning style, learning would be enhanced. But psychological research has not found that people have different learning styles. We may prefer one learning style over another, for example, seeing pictures versus reading words, but research has not shown a correlation between how people may "like" to learn, versus how much they remember later on.

When you learn something new, your brain forms new connections called synapses. Synapses are the way your brain cells (neurons) communicate with each other. As synapses strengthen, this allows for faster connections between neurons, which can speed up processing in the brain. This allows us to think faster and recall things more easily.

It was previously believed that older adults did not grow new brain cells (neurons). Newer research shows that while we do lose some brain cells as we age, we also grow new ones. Healthy older adults can produce as many new brain cells as younger people. However, older adults do not develop as many new blood vessels, and this may result in the new neurons making fewer connections than in younger people.

Intelligence is influenced by many factors. Your genes influence about 50% of your intelligence. The other part of the equation is environment, which can include a child's parenting, education, home environment, availability of resources, and nutrition.

We all know it's usually more difficult to learn a new language as adults. But it turns out that children can readily learn a new language up to the age of 18. However, in order to be as proficient as a native speaker, language lessons should start by the age of 10. After age 10 but before age 18, children can still learn a foreign language readily but because there is a shorter window for learning a new language before that ability declines, they will not be as fluent as native speakers.