10 Myths of the Brain
1. Men have bigger brains than women
Measured only by weight, men win. In 2014, English scientists measured thousands of brains, establishing that a man’s brain is opn average 8-13% larger than a woman’s. However, women’s brains seem to have better internal communication than men’s. The link between the two cerebral hemispheres - the corpus callosum - is thicker in women, indicating that women can move from a problem in one side of the brain to one at the other side faster. Scientists have also discovered differences in the distribution of the grey and white matter of the brain. Grey matter consists of brain cell nuclei, whereas white matter includes their wiring, the axons, which carry signals from one cell to another. In other words, the brain’s white areas are responsible for communication, whereas the grey ones are control centres. Women often have more grey matter, whereas men have more white matter. In men, parts of the limbic system are bigger than in women - that is where memory, fear, emotions, behaviour, and sense of smell are controlled. According to some scientists, the difference has to do with prehistoric men coping with fear and danger when hunting. In women, parts of the frontal lobe are bigger than men’s. That is where empathy is regulated, and the difference may explain why some men are more aggressive than women.
2. The brain consists of 100 billion nerve cells
According to old text books, your head holds 100 billion nerve cells. Those are the most important cells of the brain, and so, they are surrounded by different types of supporting cells that protect them against harmful substances and insulate their links, so they can send electric signals to each other fast and efficiently. However, the text books had to be rewritten after 2009, when scientists first managed to make a count. Using a new method, isotope fractionation, lab technicians dissolved and separated the parts of the brain. The scientists calculated that the brain contains 86 billion nerve cells - about 14 % fewer that what they used to believe. The difference is the same as 18 cat brains. The brain’s 86 billion nerve cells are accompanied by 85 billion supporting cells, on which they depend heavily to keep a check on everything from your innermost thoughts to how fast your fingernails grow.
In the experiment, the scientists also mapped out the distribution of nerve cells throughout the brain, discovering a big difference between the cerebrum, the cerebellum, and the brain stem. The cerebrum is by far the biggest, but only contains about one fifth of the total number of nerve cells. Instead, the supporting cells are in the majority. Scientists now want to find out why.
3. Logic is in the left cerebral hemisphere and creativity in the right hemisphere
Back in the 1960s, Nobel laureate Roger Sperry studied test subjects, whose links between the two cerebral hemispheres had been cut. He asked them to solve different problems, observing which side of the brain was active. This led to the myth of the sharply divided functions of the two hemispheres. Scientists abandoned the claims a long time ago, as brain scans show that even simple tasks activate many different areas throughout the brain. These days, scientists divide the brain into 52 Brodmann areas, which they use as a map of the brain. The areas are all important for specific tasks, but their links are just as important. Brain researchers recently mapped out fields around the forehead, behind the ear, and on the left side at the top of the brain, whose cooperation is important for intelligence.
Nothing seems to indicate that one cerebral hemisphere is responsible for more logical or creative ideas than the other one does. Myth busted!
4. The brain controls hidden senses
As we learn more about the human anatomy, scientists discover that we have much more senses than the five conventional ones. The brain receives sensory impressions from millions of receptors throughout and on the body. Receptors are small sensory units which feel pain, temperature, itching, pressure, etc - important information that the brain must use to take care of the body. The receptors are linked by nerve cells that convert the information into an electrical signal, sending it to the brain, which processes sensory impressions and reacts. If, in an unguarded moment, your hand touches a red-hot stove, receptors feel the heat, sending a fast signal to the brain, which triggers muscle motion to remove your hand. One of the senses controlled by the brain is known as proprioception. The sense is cooperation between muscle cells, the nerve cells of the spinal cord, and the cerebellum, enabling you to move your arms and legs in a controlled fashion even with your eyes closed.
5. We only use 10 % of the brain
We do not use the entire brain at the same time, but all parts are at work during a day. Scientists measure brain activity by making patients consume radioactively marked sugar. The brain is powered by sugar, and in a PET scanner, scientists can see the areas at work light up - and it's much more than 10 %. Imagine that you take a walk on the beach. When you move your muscles, you use areas on top of and at the side of the brain (motor cortex). You sense the sand - the areas right behind are active (somatosensory cortex). You see where you walk, activating the backmost part of the brain (visual cortex). When you breathe the fresh sea air, you use the innermost part of the cerebral cortex (olfactory cortex). As you walk along the beach, thoughts pass through your head, that are produced at the front of the brain (frontal lobe).
6. The brain messes with your sense of time
If you see the same image on a screen several times in a row, you will experience it as ever briefer, although the time interval is the same. If the subject changes, you will experience the time as longer again. Brain researcher David Eagleman explains the phenomenon by the fact that our brains adapt and save energy, when they encounter problems that they solved before. Known as neural adaptation, the mechanism takes place several places in the brain. Without it, we would always notice all details around us such as traffic noise, the smell of the room we are in, or clothes rubbing against our bodies. In other words, neural adaptation is the brain’s ability to prioritise inputs.
7. Adults cannot form new brain cells
For a long time, brain researchers claimed that the brain does not form new nerve cells after birth. But in the past 15-20 years, scientists have found several pockets in the brain, where new brain cells are continuously emerging. Naming the process neurogenesis, scientists have discovered that new cells appear both in the hippocampus (centre of memory) and in the subventricular zone. There, stem cells exist, which can reproduce and develop into new, fresh brain cells in only five weeks. The discoveries were a revolutionizing medical breakthrough for brain researchers, who are now studying neurogenesis closely.
If future doctors obtain the means to control and trigger the birth of new brain cells, there will be hope for patients with diseases such as Parkinson’s and Alzheimer’s, which are literally eating the brain from within. Altogether, many patients with brain injuries are suffering, because they have lost a part of the brain that cannot be replaced. If doctors become able to do that in the future, the perspectives will be far-reaching.
8. The brain can repair brain injury
Although we can rehabilitate some lost functions following brain injury, it is very difficult for the brain to repair a hole from a removed tumour or other damage to the brain tissue. If the injury arises in an area, where brain cell nuclei exist, the nerve cells will often die and be lost for good. If an area deep inside the brain is affected by brain injury, nerve cells will normally be able to recreate the lost links. But glial cells block the way, because they make up a protective network around the brain injury. Scar tissue fills the hole, at the same time restricting healthy brain cells from growing freely and preventing the lost links from growing back. People recover from brain injuries not by regrowing lost tissue, but by their brain rewiring itself around the injury. A patient's brain "plasticity" will determine how well they recover.
9. Alcohol makes you lose brain cells
When you wake up after a party, you have the exact same number of brain cells as the previous day. A team of Danish scientists discovered this in 1993, when they counted nerve cells in the cerebral cortexes of alcoholics and control subjects. The cerebral cortex is the external layer of the brain, where a wealth of brain links take place.
That's not to say alcohol won't still damage the brain. It has been shown that the white areas of the brain, where the communication wires of cells are located, shrinks in alcoholics. Alcohol breaks down the insulating layer around the wires. Without the insulating layer, the speed of brain communication falls from 120 m/s to 1 m/s, and the nerve cells become useless. We do not know exactly how alcohol does this.
In the hippocampus, the brain’s centre of memory, it looks as if alcohol affects genes that break down nerve cells, shrinks brain tissue, and restricts the formation of new cells. This explains why alcoholics can often have memory problems.
10. Baby brains develop more favourably if they listen to Mozart
In 1993, a team of scientists made a group of university students listen to Mozart before an IQ test. At the end of the experiment, it turned out that the group that had listened to classical music scored 8 IQ points more than the control group. The rumour of the Mozart effect spread fast, and soon, parents throughout the world were playing Mozart to their kids, hoping that they would grow up to be geniuses.
Although the original study was misinterpreted, certain areas of immature brains do develop differently, when they grow up with music.
According to studies, music affects brain development in several places. When kids listen to music or learn to play an instrument, new links form between the brain cells of several areas - and the kids develop better concentration skills, learning skills, and language and motor functions.
Recent studies show that as early as week 25 of the pregnancy, unborn babies are able to hear music coming from the outside. After birth, the babies can recognise the melodies played to them in their mothers’ wombs, and their brain activity is higher than in connection with melodies which they have never heard before.