Search results
Results From The WOW.Com Content Network
Arterial spin labeling utilizes the water molecules circulating with the brain, and using a radiofrequency pulse, tracks the blood water as it circulates throughout the brain. After a period of time in microseconds (enough to allow the blood to circulate through the brain), a 'label' image is captured.
Cerebral blood flow (CBF) is the blood supply to the brain in a given period of time. [8] In an adult, CBF is typically 750 millilitres per minute or 15.8 ± 5.7% of the cardiac output. [9] This equates to an average perfusion of 50 to 54 millilitres of blood per 100 grams of brain tissue per minute. [10] [11] [12]
In the 1970s, David H. Ingvar and colleagues observed blood flow in the front part of the brain became the highest when a person is at rest. [4] Around the same time, intrinsic oscillatory behavior in vertebrate neurons was observed in cerebellar Purkinje cells, inferior olivary nucleus and thalamus. [15]
The leptomeningeal collateral circulation (also known as leptomeningeal anastomoses or pial collaterals) is a network of small blood vessels in the brain that connects branches of the middle, anterior and posterior cerebral arteries (MCA, ACA, and PCA), [1] with variation in its precise anatomy between individuals. [2]
If fMRI can be used to detect the regular flow of blood in a healthy brain, it can also be used to detect the problems with a brain that has undergone degenerative diseases. Functional MRI, using haemodynamic response, can help assess the effects of stroke and other degenerative diseases such as Alzheimer's disease on brain function.
Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. [1] [2] This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases. [3]
The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including humans. [1] It is named after Thomas Willis (1621–1675), an English physician. [2]
MEG can resolve events with a precision of 10 milliseconds or faster, while functional magnetic resonance imaging (fMRI), which depends on changes in blood flow, can at best resolve events with a precision of several hundred milliseconds. MEG also accurately pinpoints sources in primary auditory, somatosensory, and motor areas.