Neurovascular Coupling

The neurovascular coupling (composed of ancient Greek neũron ' nerve cell ' , and Latin vas , (blood) vessel ) is a physiological mechanism for regulating the blood supply to the brain in order to meet the increased demand of the activated nerve tissue for oxygen and glucose by increasing the blood flow locally . This mechanism can be used to represent nerve cell activity.

Hemodynamic response

Cortical activation leads to an increase in blood flow of 10–40% with a latency of a few seconds. This is so pronounced that the relative oxygen content of the blood, the so-called oxygenation , increases, although the metabolic performance and thus the oxygen consumption of the nervous tissue concerned also increases.

How the blood flow response is mediated is still largely unclear. It is assumed that several factors interact, such as pH , potassium ions and adenosine . Some newer models assume a crucial role for the neuroglia in regulating blood flow.

Functional imaging

The representation of functional processes in the brain has made considerable progress in recent years. Such techniques can document the specific function of the organs themselves, while anatomical-morphological methods such as CT and MRI only show the structure of the living body. For a long time, measuring activity in the brain was limited to electrophysiological methods ( EEG ). Newer methods, on the other hand, make use of the fact that an increase in activity in a specific brain area, for example during movement , perception or also during cognitive performance, causes a circumscribed increase in blood flow in this region.

There are nuclear medicine ( PET , SPECT ), magnetic resonance imaging and optical ( NIRS ) approaches to functional imaging of the brain. Functional magnetic resonance imaging (fMRI) based on the oxygen saturation- dependent BOLD contrast has proven to be the standard .

literature

CS Roy , CS Sherrington : On the regulation of the blood supply of the brain . In: J Physiol . tape 11 , no. 1–2 , 1890, pp. 85-108 , PMID 16991945 ( online article ).
B. Rosengarten, M. Kaps: Combined EEG and Doppler method to determine the neurovascular coupling on the human visual cortex . In: Klin Neurophysiol . tape 38 , no. 2 , 2007, p. 128-135 , doi : 10.1055 / s-2007-977729 .

Individual evidence

↑ B. Rosengarten, T. Gerriets, E. Stolz: Functional Doppler sonography . In: M. Kaps, GM von Reutern, E. Stolz, HJ von Büdingen (Hrsg.): Ultrasound in neurology . 2nd Edition. Thieme, Stuttgart 2005, ISBN 3-13-136772-5 , chap. 13.1, p. 184 ( limited preview in Google Book search).
↑ T. Sommer: Neuroimaging: neuro-imaging methods . In: G. Hermey, C. Mahlke, M. Schwake, T. Sommer (Eds.): The Experimenter: Neurosciences . 1st edition. Spektrum Akademischer Verlag, Heidelberg 2011, ISBN 978-3-8274-2368-9 , p. 241–242 ( limited preview in Google Book search).

[1] B. Rosengarten, T. Gerriets, E. Stolz: Functional Doppler sonography . In: M. Kaps, GM von Reutern, E. Stolz, HJ von Büdingen (Hrsg.): Ultrasound in neurology . 2nd Edition. Thieme, Stuttgart 2005, ISBN 3-13-136772-5 , chap. 13.1, p. 184 ( limited preview in Google Book search).

[2] T. Sommer: Neuroimaging: neuro-imaging methods . In: G. Hermey, C. Mahlke, M. Schwake, T. Sommer (Eds.): The Experimenter: Neurosciences . 1st edition. Spektrum Akademischer Verlag, Heidelberg 2011, ISBN 978-3-8274-2368-9 , p. 241–242 ( limited preview in Google Book search).