Brain also has issues with blood supply chain, neurons act arbitrarily
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Indeed, as neuronal activity increases in response to a task, blood flow to that part of the brain exceeds the rate of energy use, causing a surplus. This enhancement is the basis for common functional imaging techniques that produce color maps of brain activity.
Neuroscientists have long recognized that neurons are greedy, hungry units that demand more energy when they are more active, and the circulatory system complies by providing the blood they need for their activity. Indeed, as neuronal activity increases in response to a task, blood flow to that part of the brain exceeds the rate of energy use, causing a surplus. This enhancement is the basis for common functional imaging techniques that produce color maps of brain activity.
Scientists used to interpret this apparent mismatch in blood flow and energy demand to show that there was no deficit in blood supply to the brain. The idea of a non-limited supply was based on the observation that only about 40 percent of the oxygen delivered to each part of the brain is used—and that this percentage actually decreases as parts of the brain become more active. It appears that the brain evolved this tendency to excessively increase blood flow to ensure that it had adequate oxygen delivery at all times.
But does blood distribution in the brain really support a demand-based system? As a neuroscientist, I had previously examined many other assumptions about the most basic facts about the brain and found them to be incorrect. To kick things off: Human brains don’t have 100 billion neurons, although they do have the most cortical neurons of any species; The degree of folding of the cerebral cortex does not indicate how many neurons are present; And it is not the bigger animals that live longer, but the ones that have more neurons in their cortex.
I believe that finding out what determines the blood supply to the brain is essential to understanding how the brain functions in health and disease. It’s as if cities need to figure out whether the current electrical grid will be sufficient to support future population growth. Brains, like cities, function only when they have an adequate supply of energy. resources in the form of highways or rivers but how can I test whether the blood flow to the brain is really demand based or not?
My freezer was full of preserved, dead brains. How do you study energy use in a brain that is no longer using energy? Fortunately, the brain leaves behind traces of its energy use through the pattern of arteries that deliver blood to it. I thought I could see the density of capillaries—the thin, one-cell-wide vessels that move gases, glucose, and metabolites between the brain and blood. These capillary networks will be preserved in the brains of my freezer.
Demand driven brain should be compared to road system. If arteries and veins are the major highways that carry goods into the city of specific parts of the brain, then capillaries are the neighborhood streets that actually deliver goods to their end users: individual neurons and the cells that work with them. Roads and highways are built on demand, and a road map shows what a demand-driven system looks like: Roads are often concentrated in parts of the country that have more people.
In contrast, a supply-limited brain should look like the riverbed of a country, which couldn’t care less about where people are located. Water will flow wherever it can, and cities will just have to adjust and make do with what they can get. Cities will likely form in the vicinity of major arteries – but in the absence of major, purposeful remodeling, their growth and activities will be limited by how much water is available.
May I know that capillaries are concentrated in parts of the brain with more neurons and are believed to require more energy, like roads and highways built in a demand-driven manner? Or shall I know that they are more like creeks and streams that penetrate the land it can penetrate, oblivious to where the most people are, where supplies are needed. What I found was clear evidence for the latter.
For both mice and rodents, capillary density ranges from 2 percent to 4 percent of the brain’s volume, regardless of how many neurons or synapses are present. Blood flows to the brain like water flows in rivers: where it can flow, not where it is needed. If blood flows regardless of need, it means that the brain is actually using the blood supply.
Only 40 percent of the oxygen supplied to the brain is actually used, this is because this is the maximum amount that can be exchanged in the bloodstream. Local arteries can deliver more blood to neurons if they start using a little more oxygen, but this comes at the cost of diverting blood away from other parts of the brain. From afar, energy use in the brain may seem demand-based – but it is actually supply-based.
Blood supply affects brain activity so why does any of this matter? Our findings provide a possible explanation for why the brain cannot truly multitask. Because blood flow throughout the brain is tightly regulated and remains essentially constant throughout the day alternating between activities, our research shows that any part of the brain that experiences an increase in activity is there. Only slightly more blood can be delivered by diverting blood flow from other parts of the brain.
Thus, the inability to do two things at the same time may result from a limited supply of blood flow to the brain. To ensure that your brain neurons stay healthy in old age, taking care of the capillaries that supply them with blood can be a good way. The good news is that there are two proven ways to do this: a healthy diet and exercise, which can be started anytime.
Disclaimer:IndiaTheNews has not edited this news. This news has been published from PTI-language feed.
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