No one can really trace back to where this notion of the human brain having a hundred billion neurons started but a researcher named Suzana Herculano-Houzel, decided to actually count it, the amount is not too far off.
The actual count is closer to 85 billion neurons.

Myth: We have 100 billion neurons in the human brain

The concept of humans having the biggest brain in regards to proportion to body size is untrue - it's another misconception.
Although we have a brain that weighs 3 lbs and measures 15 cm in length, the largest animal brain belongs to the sperm whale and it weighs a whopping 18 lbs, following second by the elephant with an 11 lbs brain.
If we're comparing brain size in proportion to body size, the shrew holds the title, due to its brain making up 10% of its body mass.

Myth: Humans have the largest brains

There is a popular notion that people may either be dominated by their right or left brain hemispheres. according to this notion, right-brained people are more creative and expressive while left-brained people are more analytical and logical.
However, as fun and as spunky as this notion might seem, it isn't really true. It has been proven that we do better at tasks when the entire brain is utilized, even for things that are typically associated with a certain area of the brain.

Myth: People are right- or left-brained

While the brain may be fragile and that damaging it results in a multitude of consequences that range from mild disruptions to our cognitive abilities to complete impairment, brain damage isn't permanent.
How one recovers from such damage depends upon its severity and the location of the injury. Remember that the brain has an impressive amount of plasticity so even after a serious brain event, the brain can often heal itself over time.

Myth: Brain Damage is Permanent

We've been long told that adults have only so many brain cells and that we never form new ones and that once these cells are lost, they're gone for good.
However, in recent years, experts have discovered evidence that the statement above isn't true. The human adult brain does indeed still form new cells throughout life, even during old age.
This process of forming new brain cells is known as neurogenesis and it happens in the area of our brain called the hippocampus.

Myth: Brain cells die permanently

While excessive and chronic alcohol abuse can certainly have dire health consequences, researchers do not believe that drinking causes neurons to die.

Myth: Drinking alcohol kills brain cells

We've heard this myth countless times from many different films or even in some of the fiction books we've read, but the reality is it continues to be a work of fiction. If this myth were true, we wouldn't be worried about brain damage that has profound consequences for our cognition and function.
The truth of the matter is that brain imaging techniques have demonstrated that the entire brain is being used even while we are asleep.

Myth: We only use 10% of our brains

Learning styles suggest that our brain has a preferred method of intaking knowledge. One popular theory suggests that our brains may prefer visual learning over kinesthetic and as fun as this sounds there is little research to back up this concept.
A large-scale study was done but found no evidence to support the use of learning style assessment instruments.

Myth: Your brain has a preferred learning style

There are still a lot of things we don't know about the brain, but researchers have dispelled a number of common myths about our most important organ.