Human brain cells called neurons communicate with each other through electrical impulses. These impulses are generated by ion channels that control the flow of ions, such as potassium and sodium. But in a startling investigation, MIT neuroscientists have shown that the number of channels in a human neuron is much smaller than expected, compared to a neuron in mammals. Researchers hypothesize that due to the low density of these vessels, the human brain could develop itself to work more effectively.
Energy used for other tasks
The researchers say that this may have helped pinpoint sources for other intense energy processes to perform complex cognitive tasks. Mark Harnett, the senior author of this study and a member of MIT’s McGovern Institute for Brain Research and associate professor of brain and cognitive sciences, explains that if the brain can save energy by decreasing the density of ion channels, it can transfer that energy to another nerve. or circuit processes.
10 Study of other organisms
Harnett and his colleagues analyzed neurons from 10 different mammals. This is the most detailed electrophysiological study of its kind. The researchers identified a map that was accurate for each species, but this did not happen in the case of humans. They found that increasing neuron size also increased the density of channels found in the neuron. The human neuron is an extraordinary exception to this rule.
Human neurons are very special
Former MIT graduate student Liu Beulie Laroche says that previous comparative studies established that human brains are similar to other mammalian brains, so we were surprised to find strong evidence that human neurons are very similar.
Functional competency assessment
Beaulieu-Laroche is the lead author of this study. His study was published last week in Nature. Neurons in mammalian brains can receive electrical signals from thousands of other cells. This input determines whether they can issue an electrical sensation called an action potential.
Found this difference three years ago
In 2018, Harnett and Beaulieu-Larosh discovered that human and mouse neurons differ in many electrical properties. In this, they differ, especially in the dendrites, the part of the neuron. Dendrites are tree-like antennae that work on receiving signals from other cells.
Ion channel density
One thing that was also found in that study was that the human neuron has a lower density of ion channels than the mouse neuron. This observation surprised the researchers because the density of ion channels was believed to be the same across all species. That is why the researchers tried to clarify the situation in the new study by intending to study the human neuron compared to the neuron of many mammals in this sense.
For this, they studied two types of voltage-gated potassium channels and the SCN channel of the fifth layer pyramidal neuron, the excitatory neuron found in the brain’s outer shell, which carries both potassium and sodium ions. They discovered that ion channel density increases with increasing neuron size in each mammal species, except the human neuron, whose ion density is much lower than expected. Researchers believe that this low density has developed due to less energy to deliver fewer ions.