There is no understating or underestimating the importance of brain for any organism on this planet. The human brain, unlike all the other brains in the world, has evolved to learn more than survival skills. It has learned to design complicated ways to have fun, experience pleasure, and to even startle itself with thrills and excitement. It has learned to manipulate the world around it to suit its needs. It has even come up with an elaborate science to learn about itself. It has produced reams and reams of biological, archaeological, and historical data about itself for many other future brains to read. So, here are some facts about the human brain that your brain might find interesting to read.
1. Human brain cells, the universe, and the internet all have similar growth patterns.
In 2012, a team of physicists from the University of California San Diego published a study based on some very interesting discoveries. During the study, the team created a computer simulation of minuscule quanta, smaller than subatomic particles, of space-time from the early universe. The simulation then connected the quanta of space-time that are causally related to each other creating a massive celestial network. They then compared the growth of this simulated network with that of other real networks such as computer networks, social networks (friend circles), and brain circuits. What they found was that all these networks expanded in a similar fashion. So, they believe that there might be a fundamental law that governs the growth of all networks, big and small.(source)
2. Despite being only two percent of the body’s weight, the human brain consumes 20% of the energy used by the entire body.
The brain of an adult human weighs between 1.2 to 1.4 kilograms. It receives 15% of all cardiac output, 20%t of total body oxygen consumption, and 25% of total body glucose consumption. It mostly relies on glucose to generate energy, though in times of low glucose levels, such as while fasting, exercising, or limited carbohydrate consumption, it can generate energy from ketone bodies. Its energy consumption is reduced during sleep, and it is believed sleep is essential to recharge the energy-giving ATP, an essential organic chemical used during metabolic processes.(source)
3. Brain tissue the size of a grain of sand contains 100,000 neurons and one billion synapses, all communicating with each other.
There are a total of more than 86 to 100 billion neurons in an adult human brain and just as many numbers of other cells. Out of these, 16 billion are present in the cerebral cortex and 69 billion are present in the cerebellum. Though there are as many as 10,000 different types of neurons in the brain, they are typically classified into three categories: sensory neurons, motor neurons, and interneurons. Each of these neurons, on an average, are connected to around 7,000 neurons. A three-year-old child’s brain has an estimated one quadrillion (1015) synapses in total. The number, however, decreases with age, and an average adult has between 100 to 500 trillion synapses.(1,2)
4. The human brain has a capacity of 2.5 petabytes, that is 2.5 million gigabytes.
There isn’t a precise way to measure the brain’s capacity to store data. But, if each neuron is capable of storing only a single memory, then there would only be a few gigabytes of storage equivalent to an iPod or a USB flash drive. However, new memories are continuously formed and old ones, or the ones that no longer serve any purpose, are continuously forgotten as neurons connect and disconnect with other neurons. Since a single neuron is capable of connecting with thousands of other neurons, it is capable of assisting with more than one memory at a time. This increases the brain’s storage capacity exponentially to something close to 2.5 petabytes. To put that into perspective, if those 2.5 petabytes of data were a digital video, it would take 300 years to finish playing it.(source)
5. About 60% of the dry mass of adult brain is made of fat; that’s approximately 25% of the total cholesterol in human body.
Most of the fat in the brain resides in the white matter which is composed of numerous bundles of myelinated axons that reach up to the gray matter. Myelin is the fatty substance that surrounds the axons or the nerve fibers and acts as an insulating layer. It helps the electrical signals jump to the uncovered axon space between it and the next myelin sheath rather than flow through the axons. This considerably speeds up signal transmission among neurons. Cholesterol is essential for myelin, and the dry mass of myelin is between 70-85% fat and between 15-30% protein, making the brain the fattest organ in human body.(1,2)
6. Though human babies are born with large brain compared to their body size, the brain doesn’t reach complete maturity until the age of 25. Until then, the brain keeps on developing.
The brain isn’t done with its development after a child is born or even after a few years of birth for that matter. During the sixth gestational week, the forebrain, midbrain, and hindbrain are developed. By the seventh gestational week, five additional structures are formed which continue developing and changing until adulthood. The cortical folds start appearing from 24 to 32 weeks of gestation. From approximately nine to 14 years of age, there is an increase in the cortical white matter, mainly the frontal and parietal cortices. The development of cortical gray matter is at a maximum at 12 years of age in the frontal and parietal cortices, and in the temporal lobes by 17 years. During the late adolescence until the mid-20s, the prefrontal cortex, also known as the “executive brain,” develops. Until 25 or 26, the myelin continues to grow in the prefrontal cortex. By this time, the brain finishes its developmental phase and starts to shrink slowly as you grow older.(1,2,3)
7. Depending on how deep a thinker you are, your brain generates as many as 12,000 to 50,000 thoughts per day.
Our brains are in continuous activity generating thoughts related to every single piece of information they store, connecting clues, predicting possibilities, ruminating past, and discarding thoughts that are not useful. The number of these thoughts vary, and there are different estimates from different researchers. While some put their number between 12,000 to 50,000, some say it’s as many as 60,000. However, the sad part is 70-80% of these thoughts are negative.(source)
8. When you orgasm, your brain releases so much dopamine that a brain scan would resemble that of someone on heroin.
Dopamine, oxytocin, and prolactin are the chemicals that affect your mood, the feeling of satiation, desire for intimacy, and also your susceptibility to addictions. Dopamine, especially, is the primary neurotransmitter of the brain’s reward system. Activities like eating, sex, or recreational drug use result in its release and hence you feel pleasure. When you are sexually aroused through physical contact, its levels rise making you feel good. Then, when an orgasm is reached, there would be a dopamine brainstorm which is similar to the effects of heroin on a brain.(1,2)
9. There are no nociceptors in the brain, so the brain itself cannot feel pain.
The nociceptors are the nerve endings of sensory neurons which respond to dangerous or potentially dangerous stimuli by sending danger signals to the brain and spinal cord. The brain requests the hypothalamus to release hormones that can soothe or alleviate the painful sensation. However, as the cells responsible for making nociceptors are different from those that make up the brain, there are no pain receptors in the brain. This is why no anesthesia is required while operating on brain tissue as the brain cannot feel any pain.
The headaches, brain freeze, and migraines are actually pains from different parts of your face like the sinus or the top of your mouth. The reason you feel pain inside your brain is that the brain is not very good at identifying the exact location. Another example is how people having a heart attack feel pain in their arm instead of at the heart.(source)
10. The brain is so plastic that it can rewire itself to let you have a normal life even after half of your brain is removed.
The brain is not completely hardwired with fixed circuits of neurons, be it in adults or children. It has a quality known as neuroplasticity which enables it to continually alter itself throughout an individual’s life. Neuroplasticity is commonly observed in children who undergo hemispherectomy for epilepsy, a surgery that requires removing/disabling half the brain or disconnecting the two cerebral hemispheres, and also in individuals who undergo surgery for brain trauma, stroke, epilepsy, or other such problems. It is also one of the reasons why scientists believe the left and right hemispheres do not have specifically designated roles in learning and development.(source)