Haemodynamic response

Haemodynamic response

Haemodynamics is a medical term for the dynamic regulation of the blood flow in the brain. It is the principle on which functional magnetic resonance imaging is based.

Neurons, like all other cells, require energy to function. This energy is supplied in the form of glucose and oxygen (the oxygen being carried in haemoglobin). The blood supply of the brain is dynamically regulated to give active neural assemblies more energy whilst inactive assemblies receive less energy [cite book
last = Siesjo
first = Bo K.
authorlink = Bo K. Siesjo
title = Brain Energy Metabolism
publisher = Wiley
date = 1978
location = New York
pages = 612
id = 0 471 99515 0
] .

Molecular biology of hemodynamic regulation

The precise mechanism behind neurovascular coupling is currently under active research and furious debate, but roughly the following model has gained consensus:
# Active excitatory neurons release the neurotransmitter glutamate
# Glutamate opens NMDA receptors on other neurons which allows calcium ions into the neuron
## Calcium activates nitric oxide synthase which produces nitric oxide
## Nitric oxide diffuses out and dilates smooth muscle surrounding local arterioles
## This dilation allows more blood into the local capillaries
## Hence more oxygen and glucose reaches the neurons [cite journal
last = Stefanovic
first = Bojano J.
authorlink = David J Rossi
coauthors = Wolfram Schwindt, Mathias Hoehn and Afonso C Silva
title = Functional uncoupling of hemodynamic from neuronal response by inhibition of neuronal nitric oxide synthase
journal = Journal of Cerebral Blood Flow & Metabolism
volume = 27
pages = 741–754
date = 2007
url = http://www.nature.com/jcbfm/journal/v27/n4/full/9600377a.html
doi = 10.1038/sj.jcbfm.9600377
accessdate = 2007-05-22
]
# Glutamate also binds to the metabotropic glutamate receptor on astrocytes
## This allow calcium into the astrocyte
## Which activates phospholipase A2 (PLA2)
## Which produces arachidonic acid (AA)
## Which is converted by cyclo-oxygenase
## Into PGE2 and released through the astrocytic endfeet
## Which dilates local smooth muscle and allows greater blood flow [cite journal
last = Rossi
first = David J
authorlink = David J Rossi
title = Another BOLD role for astrocytes: coupling blood flow to neural activity
journal = Nature Neuroscience
volume = 9
pages = 159–161
date = 2006
url = http://www.nature.com/neuro/journal/v9/n2/full/nn0206-159.html
doi = 10.1038/nn0206-159
accessdate = 2007-05-22
]

References

External links

* [http://www.loni.ucla.edu/SVG/index.php?vid=261 An animation of neurovascular coupling]


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Brain–computer interface — Neuropsychology Topics Brain computer interface …   Wikipedia

  • Functional magnetic resonance imaging — Functional MRI or functional Magnetic Resonance Imaging (fMRI) is a type of specialized MRI scan. It measures the haemodynamic response related to neural activity in the brain or spinal cord of humans or other animals. It is one of the most… …   Wikipedia

  • Brain-computer interface — A brain computer interface (BCI), sometimes called a direct neural interface or a brain machine interface, is a direct communication pathway between a human or animal brain (or brain cell culture) and an external device. In one way BCIs,… …   Wikipedia

  • Nikos Logothetis — (born 1950 in Istanbul) is Greek a biologist and neuroscientist. Logothetis is director of the department Physiology of Cognitive Processes at the Max Planck Institute for Biological Cybernetics in Tübingen. He studied mathematics and music in… …   Wikipedia

  • HRF — may mean:* Hostage Rescue Force Egyptian police unit responsible for hostage situations and counter terrorism operations * Homeland Reserve Forces * Hotell och Restaurang Facket, the Swedish Hotel and Restaurant Workers Union * Haemodynamic… …   Wikipedia

  • Stanley Salmons — (1939 ) was born in Clapton, East London, and was educated at St. Marylebone Grammar School. Awarded a Royal Scholarship, he attended Imperial College London, from which he graduated in Physics and went on to gain a D.I.C. in Electronics and… …   Wikipedia

  • Leukocyte extravasation — Neutrophils extravasate from blood vessels to the site of tissue injury or infection during the innate immune response Leukocyte extravasation is the movement of leukocytes out of the circulatory system, towards the site of tissue damage or… …   Wikipedia

  • Acute liver failure — is the appearance of severe complications rapidly after the first signs of liver disease (such as jaundice), and indicates that the liver has sustained severe damage (loss of function of 80 90% of liver cells). The complications are hepatic… …   Wikipedia

  • Mechanical ventilation — In architecture and climate control, mechanical or forced ventilation is the use of powered equipment, e.g. fans and blowers, to move air  see ventilation (architecture). Mechanical ventilation Intervention …   Wikipedia

  • Horse colic — This page is about Horse colic. For other types of colic, see Colic. Colic in horses is defined as abdominal pain, but it is a clinical sign rather than a diagnosis. The term colic can encompass all forms of gastrointestinal conditions which… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”