MIT researchers were amazed to see that Human neurons have a lower than expected density of ion channels compared to other mammals. Ion channels generate electrical impulses through which neurons communicate. This is another surprising recent observation about the structure of the brain. newly inform usThe density of synapses in mouse brains is greater than in monkeys’ brains.
Scientists hypothesised that the human brain evolved to function more efficiently due to a lower density of ion channels, allowing it to provide energy for other processes required for complex cognitive tasks. If the brain can save energy by reducing the density of ion channels, it can use the saved energy for other processesProfessor Mark Harnett of the McGovern Institute for Brain Research at the Massachusetts Institute of Technology said.
Together with Dr. Lou Beaulieu-Laroche, they compared the neurons of several mammalian species, looking for patterns underlying ion channel expression. They studied two types of voltage-dependent potassium channels and the HCN channel of pyramidal neurons in the fifth layer of the cerebral cortex. The researchers studied 10 mammals: Etruscan shrews, Mongolian shrews, mice, rats, rabbits, sea monkeys, macaques, guinea pigs, ferrets, and human tissue from epilepsy patients. They have conducted the most comprehensive electrophysiology study of this kind.
Scientists have found that as the size of neurons increases, the density of ion channels increases. Such dependence is found in 9 out of 10 studied species. Species with larger neurons and therefore a reduced surface-to-volume ratio have an increased ionic conductivity of their cell membranes. The exception to this rule is people.
This was an astonishing discovery as previous comparative studies had shown that the human brain is structured like the brains of other mammals. Therefore, it surprised us that human neurons are differentsays Beaulieu Laroche.
Scientists admit that the increased density of ion channels was a surprise to them, but when they began to think about it, it turned out to be common sense. In the brain of a small Etruscan shrew, which is full of very small neurons, its density in a certain volume is greater than in the brain of a rabbit, which contains much larger neurons. However, since neurons in rabbits have a higher ion channel density, for a given brain volume, both types have the same ion channel density. This brain structure is consistent across nine different species of mammals. The cerebral cortex appears to be trying to maintain the same number of ion channels per unit volume. This means that for a unit volume of the cerebral cortex, the energy cost of ion channels is the same for different species. Turns out the human brain is an exception here.
Scientists believe that the lower density of ion channels in Homo sapiens brains may have evolved as a way to reduce the energy costs of transporting ions, allowing the brain to use this energy for something else, such as creating more complex connections between neurons.
We believe that as a result of evolution, the human brain has “disengaged” from this striatum, reducing the size of the cerebral cortex and becoming more energy efficient, so our brains use less ATP per unit volume than other species.Harnett says.
The scientist hopes that in the future it will be possible to determine the purpose of using the energy provided by the brain, and we will find out if there are any special genetic mutations in humans, thanks to the neurons in our cerebral cortex. More energy efficient. The scientists also want to check whether the phenomenon of decreased ion channel density also occurs in other primates.
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