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Image source: Pixabay Source: MIT Translated by Zheng Xinyuan Edited by Wei Xiao Neurons communicate with each other through electrical impulses, which are generated by ion channels that control the flow of potassium and sodium plasma
.
In a new study, neuroscientists at the Massachusetts Institute of Technology (Massachusetts Institute of Technology) found a surprising conclusion: Compared with other mammalian neurons, the number of ion channels in human neurons is greater than expected.
Much less
.
The researchers put forward a hypothesis: this reduction in ion channel density may contribute to the efficient evolution of the human brain, enabling it to transfer resources to other energy-intensive processes required to perform complex cognitive tasks
.
"If the brain can save energy by reducing the density of ion channels, it can use this energy for interactions between other neurons or neural circuit processes
.
" Mark Harnett said
.
He is an associate professor of brain and cognitive science at the McGovern Institute for Brain Research at MIT and the corresponding author of the study
.
Harnett and his colleagues analyzed the neurons of 10 different mammals, which is the most extensive study of its kind in electrophysiology
.
They confirmed a "construction method" that applies to every species they observe—except humans
.
They found that as the size of the neuron increases, the ion channel density of the neuron also increases
.
However, human neurons proved to be a surprising exception to this rule
.
"Previous comparative studies have shown that the structure of the human brain is similar to that of other mammals
.
So we were surprised to find strong evidence of the specificity of human neurons
.
" said former MIT graduate student Lou Beaulieu-Laroche
.
Beaulieu-Laroche is the first author of the study, which was published in the journal Nature on November 10
.
The neurons in the mammalian brain can receive electrical signals from thousands of other cells, and this input determines whether they emit action potentials
.
In 2018, Harnett and Beaulieu-Laroche found that human and rat neurons differ in some electrical properties
.
These differences mainly exist in the dendrites of neurons (used to receive and process dendrites from other cells)
.
One finding of the study is that the ion channel density of human neurons is lower than that of rat brain neurons
.
Researchers were surprised by this, because the academic community generally believes that the ion channel density is constant among different species
.
In the new study by Harnett and Beaulieu-Laroche, they decided to compare neurons from different mammals to see if they could find a rule that regulates the expression of ion channels
.
They studied two types of voltage-gated potassium ion channels and HCN channels (Hyperpolarization-activated cyclic nucleotide–gated channels) that can pass potassium and sodium at the same time
.
These channels exist in the fifth cortex pyramidal neurons-an excitatory neuron found in the cerebral cortex
.
They obtained brain tissues from 10 mammalian species: small smelly shrews (one of the smallest known mammals), gerbils, mice, rats, guinea pigs, ferrets, rabbits, marmosets and macaques, as well as in the brain Human tissue removed from a patient with epilepsy during a surgical operation
.
This diversity allows their research to cover various cortical thicknesses and neuron sizes in the mammalian kingdom
.
The researchers found that in almost all mammals they observed, the density of ion channels in neurons increased as the cell size increased
.
An exception to this rule is human neurons, whose ion channel density is much lower than expected
.
Harnett said that this finding of increased cross-species channel density is surprising, because the more channels, the more energy is required to pump ions in and out of the cell
.
When researchers began to think about the number of channels in the cerebral cortex as a whole, he said, this became reasonable
.
The tiny brain of the little stinky shrew is packed with very small neurons
.
The rabbit's neurons are much larger
.
Compared with the same volume of rabbit brain tissue, the number of neurons in a given volume is much higher
.
But because the ion channel density of rabbit neurons is higher, in a given volume of tissue, the ion channel density of these two animals (and any non-human species analyzed by the researchers) is the same
.
"This method of construction is consistent across nine different mammals," Harnett said
.
"It seems that the cerebral cortex tries to keep the number of ion channels per unit volume the same in all species
.
This means that for a given volume of the cerebral cortex, the energy consumption is the same, at least for ion channels
.
" Energy efficiency, however, is human.
The brain showed a significant deviation from this construction method
.
The researchers found that in a given volume of human brain tissue, the density of ion channels did not increase, but greatly decreased
.
Researchers believe that this lower channel density may be a way of pumping ions that the human brain has evolved to consume less energy
.
So the brain can use this energy for other purposes, such as creating more complex synaptic connections between neurons, or firing action potentials at a higher rate
.
"We think that humans have evolved to get rid of the previous construction method that limits the size of the cerebral cortex
.
They have found a more energy-efficient method, so compared with other species, you consume ATP per unit volume.
Less," Harnett said
.
Now, he hopes to study where this extra energy may go, and whether there are specific genetic mutations that help human cortical neurons achieve this high efficiency
.
In addition, the researchers also hope to further explore the brains of primate species that are more closely related to humans, hoping to find out whether their neurons also show a similar decrease in ion channel density.
.
Original link: https://
.
In a new study, neuroscientists at the Massachusetts Institute of Technology (Massachusetts Institute of Technology) found a surprising conclusion: Compared with other mammalian neurons, the number of ion channels in human neurons is greater than expected.
Much less
.
The researchers put forward a hypothesis: this reduction in ion channel density may contribute to the efficient evolution of the human brain, enabling it to transfer resources to other energy-intensive processes required to perform complex cognitive tasks
.
"If the brain can save energy by reducing the density of ion channels, it can use this energy for interactions between other neurons or neural circuit processes
.
" Mark Harnett said
.
He is an associate professor of brain and cognitive science at the McGovern Institute for Brain Research at MIT and the corresponding author of the study
.
Harnett and his colleagues analyzed the neurons of 10 different mammals, which is the most extensive study of its kind in electrophysiology
.
They confirmed a "construction method" that applies to every species they observe—except humans
.
They found that as the size of the neuron increases, the ion channel density of the neuron also increases
.
However, human neurons proved to be a surprising exception to this rule
.
"Previous comparative studies have shown that the structure of the human brain is similar to that of other mammals
.
So we were surprised to find strong evidence of the specificity of human neurons
.
" said former MIT graduate student Lou Beaulieu-Laroche
.
Beaulieu-Laroche is the first author of the study, which was published in the journal Nature on November 10
.
The neurons in the mammalian brain can receive electrical signals from thousands of other cells, and this input determines whether they emit action potentials
.
In 2018, Harnett and Beaulieu-Laroche found that human and rat neurons differ in some electrical properties
.
These differences mainly exist in the dendrites of neurons (used to receive and process dendrites from other cells)
.
One finding of the study is that the ion channel density of human neurons is lower than that of rat brain neurons
.
Researchers were surprised by this, because the academic community generally believes that the ion channel density is constant among different species
.
In the new study by Harnett and Beaulieu-Laroche, they decided to compare neurons from different mammals to see if they could find a rule that regulates the expression of ion channels
.
They studied two types of voltage-gated potassium ion channels and HCN channels (Hyperpolarization-activated cyclic nucleotide–gated channels) that can pass potassium and sodium at the same time
.
These channels exist in the fifth cortex pyramidal neurons-an excitatory neuron found in the cerebral cortex
.
They obtained brain tissues from 10 mammalian species: small smelly shrews (one of the smallest known mammals), gerbils, mice, rats, guinea pigs, ferrets, rabbits, marmosets and macaques, as well as in the brain Human tissue removed from a patient with epilepsy during a surgical operation
.
This diversity allows their research to cover various cortical thicknesses and neuron sizes in the mammalian kingdom
.
The researchers found that in almost all mammals they observed, the density of ion channels in neurons increased as the cell size increased
.
An exception to this rule is human neurons, whose ion channel density is much lower than expected
.
Harnett said that this finding of increased cross-species channel density is surprising, because the more channels, the more energy is required to pump ions in and out of the cell
.
When researchers began to think about the number of channels in the cerebral cortex as a whole, he said, this became reasonable
.
The tiny brain of the little stinky shrew is packed with very small neurons
.
The rabbit's neurons are much larger
.
Compared with the same volume of rabbit brain tissue, the number of neurons in a given volume is much higher
.
But because the ion channel density of rabbit neurons is higher, in a given volume of tissue, the ion channel density of these two animals (and any non-human species analyzed by the researchers) is the same
.
"This method of construction is consistent across nine different mammals," Harnett said
.
"It seems that the cerebral cortex tries to keep the number of ion channels per unit volume the same in all species
.
This means that for a given volume of the cerebral cortex, the energy consumption is the same, at least for ion channels
.
" Energy efficiency, however, is human.
The brain showed a significant deviation from this construction method
.
The researchers found that in a given volume of human brain tissue, the density of ion channels did not increase, but greatly decreased
.
Researchers believe that this lower channel density may be a way of pumping ions that the human brain has evolved to consume less energy
.
So the brain can use this energy for other purposes, such as creating more complex synaptic connections between neurons, or firing action potentials at a higher rate
.
"We think that humans have evolved to get rid of the previous construction method that limits the size of the cerebral cortex
.
They have found a more energy-efficient method, so compared with other species, you consume ATP per unit volume.
Less," Harnett said
.
Now, he hopes to study where this extra energy may go, and whether there are specific genetic mutations that help human cortical neurons achieve this high efficiency
.
In addition, the researchers also hope to further explore the brains of primate species that are more closely related to humans, hoping to find out whether their neurons also show a similar decrease in ion channel density.
.
Original link: https://
