zhiting xu
- Jul 29, 2023
- 3 min read

How much do you think you understand your brain?

In a survey-based study, a majority of respondents of over 80% claimed to have some knowledge on how their brain works. However, when presented with a simple question of whether they agree that humans only utilize 10% of their brains or not, a large proportion exhibited agreement. This is a long-standing myth, but the truth is that nearly every thought and action humans engage in utilizes various parts of the brain, which amount to much more than 10 percent. The widespread belief based on a misconception illustrates that people do not truly understand their own brains.

Physiology textbooks would be incomplete without a section on the brain. Actions described in other sections of the human body, the reception of stimuli, and the corresponding responses all involve the central nervous system, with a significant portion within the brain. A detailed understanding of the human brain contributes to our comprehension of human thoughts and behaviors. For example, it is a well-established fact that human knowledge is limited. We cannot simultaneously perform two complex tasks due to selective attention. It is impossible to engage in activities such as driving, listening, chatting, texting and internet browsing simultaneously while maintaining both success and safety. Even the simplest tasks, such as tapping one's head while rubbing one's stomach or drawing circles with the left hand and squares the right, cannot be accomplished simultaneously without dedicated effort. But why is this the case?

Many people believe that these limitations reflect the fact that different behaviors take up shared resources within the brain. If a the processing leading to a single action consumes a large amount of brain resources, there is not enough space left for another action. So, then, what exactly are these limited "brain resources"?

To understand how the brain works, we must start with the basics. The brain primarily relies on oxygen and glucose, both of which are delivered to the brain via the bloodstream. The brain is the primary consumer of these metabolic substances in the human body, accounting for approximately 20% of the oxygen and calories consumed. As long as there is no oxygen deficiency or malnutrition, our bodies can provide sufficient raw materials for the control center of our brain. The basic unit of the nervous system is the neuron, and the average human brain contains nearly 86 billion neurons. This vast amount of data storage about the brain may lead people to think that humans only use 10% of their brains, suggesting that there are many untapped possibilities. Despite that, in reality, based on modern medical neuroimaging studies of the human brain, different parts of the brain can be activated during different actions and at different times, and yes, it is certain that at some point, more than 10% is utilized.

If our brains are stuffed with neurons, how do we explain our limitations in terms of our cognitive abilities? Why can't we just be able to do multiple things simultaneously? The most plausible explanation lies in the connections between neurons.

For example, we know that many neurons in the visual cortex inhibit each other (Beck & Kastner, 2009). When one neuron fires, it inhibits the signals of neighboring neurons. No two neurons in the brain are the same, and the competitive behavior between them partially limits the brain's ability to simultaneously respond to visual information. Although competitive clues among neurons such as this one may account for many of our limitations, we can still strive to maximize the utilization of our brains, as always.