As is often said, man is the crown of creation.And we became a “crown” only because we have a more perfect brain than our smaller brothers. But what are the differences? I must say right away that the volume of gray matter does not matter. The human brain weighs only 1-2 kg. For example, in a sperm whale, its weight is 9 kg, the brain of an elephant weighs 5 kg. However, their cognitive abilities are far from those of humans. Do you think it's all about the number of neurons? This is also not true, since the black dolphin has more neurons in the brain than humans. However, there is still a difference. As scientists at the Massachusetts Institute of Technology suggest, they lie in the structural features of the neurons in the brain. Thanks to this, according to scientists, the human brain is more energy efficient.
What is the difference between neurons in the human brain?
Neurons are special cells thatcommunicate with each other through electrical impulses generated by ion channels. The latter are special proteins that the cell membrane contains. Neurons are responsible for a wide variety of brain functions. There are even those who are responsible for consciousness. As it turned out, contrary to expectations, neurons in the human brain contain fewer channels than in animals.
It was previously known that neurons can havedifferent sizes, and also differ in branches responsible for transmitting and receiving impulses. As you might guess, a large neuron has more channels than a small one. However, if you compare a large neuron, for example, a sperm whale, and a mouse, then, as previously assumed, they work in the same way.
On the one hand, it is, but only whencomparison occurs between the neurons of most animal species. As for human neurons, then, as shown by a study that was published in the publication Nature, they differ in their electrophysiological parameters.
As the authors of the work suggest, the reductionthe number of channels could help the human brain develop and work more efficiently. Conserving resources allows the brain to direct them to other energy-intensive processes that occur when performing complex cognitive tasks.
“If the brain can save energy bydecrease in ion channel density, it can spend this energy on other neural or chain processes, ”says Mark Harnett, assistant professor in the Department of Brain and Cognitive Sciences, a member of the McGovern Institute for Brain Research at MIT, and senior author of the study.
Human evolution made the brain more energy efficient
Researchers analyzed 10 neuronsvarious mammals, including rats, guinea pigs, rabbits, marmoset monkeys, macaques, etc. The authors of the work studied the density of ion channels located in the membranes of neurons in a particular layer of the cortex.
As neurons grow in different animals,as it turned out, the channel density also increases. For example, primates have more neurons than shrews, so the density of ion channels is also higher. But such a difference can be seen when comparing individual neurons. But if we compare a certain identical volume of the brain, then the number of ion channels in these animals is the same.
This is due to the fact that a small animal,such as a mouse, neurons are smaller than those of a macaque. If, roughly speaking, you take two small samples of the brains of two animals, the mouse in the sample will have more neurons than the macaque. But since the density of ion channels in macaques is higher, their number in animals is the same. As a result, the electrical properties of different animals are also the same, be it a mouse, a rabbit, a shrew or a monkey. However, this rule does not apply to humans.
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In a sample of the human brain, there was lesschannels, despite the large size of the neurons. The authors of the work explain that ion channels consume a lot of energy. Accordingly, the more channels there are, the more energy is required for the brain to synthesize impulses.
“We think humans have evolved, that is, we have found a way to become more energy efficient so that they use less energy compared to other animals,” says Harnett.
Thus, it was possible to find out that the human braindiffers from the brain of animals at the cellular level. This difference is likely to affect how the brain works. In the near future, researchers plan to study the brain of great apes. On the evolutionary ladder, they are our closest neighbors. Perhaps this will allow us to understand when such changes occurred in the human brain, and what genetic processes led to this. Finally, I note that the brain of modern people has become not only more energy efficient, but also decreased in size, as we talked about earlier.