Using imaging technologies, they have observed that when neurons start to fire there is an accompanying increase in blood flow to area of the brain that is active.
This is an important question because unlike other parts of the body, the brain resides in a confined space which restricts the amount of blood that is on hand at any given moment. Consequently, the circulatory system must be precisely tuned, constantly reacting to shifts in demand by diverting and increasing blood flow to where it is needed most.
The system that brings blood to the brain is akin to a road network that serves a city. While arteries are the main supply routes into the brain, blood ultimately delivers its payload of oxygen to its final destination via a vast web of smaller capillaries — or microvessels — which permeate brain tissue.
While some scientists have theorized that the main arteries are responsible for responding to increases in demand — essentially by dilating in order to increase blood flow — Nedergaard and her colleagues speculated that the capillaries must play a central role because they are closer to the action and would be the first to detect the need for more oxygen. To test this theory the researchers created a miniature race track that mimicked the capillaries in the brain and placed red blood cells at the starting line on one end.
When the oxygen level in the fluid outside the artificial capillaries was high, the cells took their time cross to the other side. If more than twice the atmospheric oxygen concentration was available, the energy metabolism was saturated and oxygen was abundantly present in the brain. However, nerve cells with increased activity consume more oxygen.
In order to better understand how information is processed in the brain, knowledge of the relationship between oxygen availability and brain activity is essential. The scientists' results provide initial insight into this and are an important basis for further investigations of the brain's energy balance in future experiments and for measuring oxygen consumption for various nerve cell functions. This could also be relevant from a medical point of view, for example to better understand the consequences of oxygen deficiency in the brain or to better interpret the information on brain activity obtained with imaging techniques.
Note: Content may be edited for style and length. Science News. Relationship between oxygen consumption and neuronal activity in a defined neural circuit. ScienceDaily, 6 July Neurobiology: How much oxygen does the brain need?. Sudden severe headache with no known cause. Unexplained dizziness, unsteadiness, or sudden falls, especially with any of the other signs.
Reprinted with permission from The National Institute of Neurological Disorders and Stroke High blood pressure - Eat a balanced diet, maintain a healthy weight, and exercise to reduce blood pressure. Drugs are also available.
Cigarette smoking - Don't start smoking and if you do smoke, quit! Heart disease - Your doctor will treat your heart disease and may also prescribe medication to help prevent the formation of clots. Diabetes - Treatment can delay complications that increase the risk of stroke. Transient ischemic attacks - These are brief episodes of stroke's warning signs and can be treated with drugs or surgery.
Did you know? Each year there are , people one every 45 seconds in the United States who suffer a stroke. Statistic from American Stroke Association The word "carotid" carotid artery comes from the Greek word karotis meaning "deep sleep. Source: Nilsson, G. Chudler All Rights Reserved.
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