fMRI: how brain directs blood supply (Introduction)

by David Turell , Thursday, July 22, 2021, 19:42 (1009 days ago) @ David Turell

Calcium and neuron signals:

https://www.sciencedaily.com/releases/2021/07/210721190113.htm

Unlike the rest of the body, there is not enough real estate in the brain for stored energy. Instead, the brain relies on the hundreds of miles of blood vessels within it to supply fresh energy via the blood. Yet, how the brain expresses a need for more energy during increased activity and then directs its blood supply to specific hot spots was, until now, poorly understood.

Now, University of Maryland School of Medicine and University of Vermont researchers have shown how the brain communicates to blood vessels when in need of energy, and how these blood vessels respond by relaxing or constricting to direct blood flow to specific brain regions.

"...the researchers say that understanding how the brain directs energy to itself in intricate detail can help determine what goes wrong in conditions like Alzheimer's disease and dementia, where faulty blood flow is a predictor for cognitive impairment. If the brain does not get blood to where it needs it when it needs it, the neurons become stressed, and over time they deteriorate ultimately leading to cognitive decline and memory problems.

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"They found that when neurons fire electrical signals, they cause an increase in calcium in the cells lining the blood vessels. Then enzymes detect this calcium and direct the cells to make nitric oxide. Nitric oxide is a hormone (and a gas) that causes muscle-like cells around blood vessels to relax, which then widens the vessels allowing more blood to flow in.

"'Capillaries were traditionally thought as simple conduits for red blood cells, and the barrier between the blood and brain," says co-senior author Mark T. Nelson, PhD, University of Vermont Distinguished Professor and Chair of Pharmacology. "Here, we revealed an unknown universe of calcium signaling in capillaries, and much like traffic lights, these calcium signals direct vital nutrients to nearby active neurons.'"

Comment: This is amazingly complex system. The mammalian, not storing energy, must supply it by a precise control over blood supply of oxygen and nutrients to allow responses and thought. Too complex to be designed by chance mutations. Only a designer fits.