The 10 percent myth was also debunked in a study published in Frontiers in Human Neuroscience. One common brain imaging technique, called functional magnetic resonance imaging fMRI , can measure activity in the brain while a person is performing different tasks. Using this and similar methods, researchers show that most of our brain is in use most of the time, even when a person is performing a very simple action.
The percentage of the brain in use at any given time varies from person to person. It also depends on what a person is doing or thinking about. In an article published in a edition of the journal Science , psychologist and author William James argued that humans only use part of their mental resources.
However, he did not specify a percentage. This may have contributed to the 10 percent myth. The myth has been repeated in articles, TV programs, and films, which helps to explain why it is so widely believed.
Eating well improves overall health and well-being. It also reduces the risk of developing health issues that may lead to dementia , including:. There is a selection of walnuts and pecans available for purchase online.
Cardiovascular activities, such as walking briskly for 30 minutes a day, can be enough to reduce the risk of brain function declining. The more a person uses their brain, the better their mental functions become. For this reason, brain training exercises are a good way to maintain overall brain health. A recent study conducted over 10 years found that people who used brain training exercises reduced the risk of dementia by 29 percent.
There are a number of other popular myths about the brain. These are discussed and dispelled below. Many believe that a person is either left-brained or right-brained, with right-brained people being more creative, and left-brained people more logical. However, research suggests that this is a myth — people are not dominated by one brain hemisphere or the other. A healthy person is constantly using both hemispheres. It is true that the hemispheres have different tasks. And it has its own specialized areas—one of which is devoted to processing language.
In recent years, brain scans have started to show that the particular way neurons connect to one another is also part of the story. A key tool in these studies is magnetic resonance imaging MRI —in particular, a version known as diffusion tensor imaging. This technique can visualize the long fibers that extend out from neurons and link brain regions without having to remove a piece of skull. Like wires, these connections carry electrical information between neurons. And the aggregate of all these links, also known as a connectome, can provide clues about how the brain processes information.
A persistent question about connectomes has to do with what, if anything, distinctive wiring patterns have to do with the evident cognitive differences in a mouse, a monkey or a human.
A new methodology called comparative connectomics has identified some general rules of brain wiring across species that may help provide answers. In the meantime, it has also found some unique facets of the human connectome and discovered changes in the cells charged with the upkeep of brain wiring. Together these evolutionary innovations seem to keep information flowing efficiently through a large human brain. And when they are disrupted, they may give rise to psychiatric disorders.
Hypothetically, the most efficient connectome would follow a one-to-many design, with each nerve cell connecting to all of the others. But this approach is prohibitively unworkable because it requires a lot of space to house all these connections and energy to keep them functioning. Alternatively, a one-to-one design, in which each neuron connects to only a single other neuron would be less challenging—but also less efficient: information would have to traverse enormous numbers of nerve cells like stepping-stones to get from point A to point B.
Assaf came upon his research in a somewhat roundabout way: What began as a weekend hobby of imaging bat brains with his Tel Aviv colleague, Yossi Yovel, turned into a seven-year-long exploration of as many postmortem mammalian brains as they could borrow from a nearby veterinary institute.
The investigators looked at a variety of the organs—from the smallest bat brain, which required a magnifying glass to inspect, all the way to the human heavyweight. In between those examples were the brains of giraffes, honey badgers and cows. Among all of them, the team found the same patterns of connections at work: the number of stepping stones to get from one place to another was roughly the same in each of the organs.
Differing brains used a similar wiring design. The cortex is gray because nerves in this area lack the insulation that makes most other parts of the brain appear to be white. The folds in the brain add to its surface area and therefore increase the amount of gray matter and the quantity of information that can be processed.
Deep within the brain, hidden from view, lie structures that are the gatekeepers between the spinal cord and the cerebral hemispheres. These structures not only determine our emotional state, they also modify our perceptions and responses depending on that state, and allow us to initiate movements that you make without thinking about them.
Like the lobes in the cerebral hemispheres, the structures described below come in pairs: each is duplicated in the opposite half of the brain. The hypothalamus 10 , about the size of a pearl, directs a multitude of important functions.
It wakes you up in the morning, and gets the adrenaline flowing during a test or job interview. The hypothalamus is also an important emotional center, controlling the molecules that make you feel exhilarated, angry, or unhappy. Near the hypothalamus lies the thalamus 11 , a major clearinghouse for information going to and from the spinal cord and the cerebrum. An arching tract of nerve cells leads from the hypothalamus and the thalamus to the hippocampus This tiny nub acts as a memory indexer—sending memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrieving them when necessary.
The basal ganglia not shown are clusters of nerve cells surrounding the thalamus. They are responsible for initiating and integrating movements. The brain and the rest of the nervous system are composed of many different types of cells, but the primary functional unit is a cell called the neuron. All sensations, movements, thoughts, memories, and feelings are the result of signals that pass through neurons.
Neurons consist of three parts. The cell body 13 contains the nucleus, where most of the molecules that the neuron needs to survive and function are manufactured. Dendrites 14 extend out from the cell body like the branches of a tree and receive messages from other nerve cells. Signals then pass from the dendrites through the cell body and may travel away from the cell body down an axon 15 to another neuron, a muscle cell, or cells in some other organ. The neuron is usually surrounded by many support cells.
Some types of cells wrap around the axon to form an insulating sheath This sheath can include a fatty molecule called myelin, which provides insulation for the axon and helps nerve signals travel faster and farther. Or axons may be very long, such as those that carry messages from the brain all the way down the spinal cord.
Scientists have learned a great deal about neurons by studying the synapse—the place where a signal passes from the neuron to another cell. When the signal reaches the end of the axon it stimulates the release of tiny sacs These sacs release chemicals known as neurotransmitters 18 into the synapse The neurotransmitters cross the synapse and attach to receptors 20 on the neighboring cell.
These receptors can change the properties of the receiving cell. If the receiving cell is also a neuron, the signal can continue the transmission to the next cell.
Neurotransmitters are chemicals that brain cells use to talk to each other. Some neurotransmitters make cells more active called excitatory while others block or dampen a cell's activity called inhibitory. Acetylcholine is an excitatory neurotransmitter because it generally makes cells more excitable. It governs muscle contractions and causes glands to secrete hormones. Glutamate is a major excitatory neurotransmitter. Too much glutamate can kill or damage neurons and has been linked to disorders including Parkinson's disease, stroke, seizures, and increased sensitivity to pain.
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