Increased blood flow detected by fMRI scans?

Liar42 liar42 at aol.com
Fri Oct 26 20:42:45 EST 2001


1. > Marcus E. Raichle, a brain-scan expert at Washington University, points to
other research that suggests that neural activity associated with signal inputs
burns glucose without using oxygen. This anaerobic (...) <

2. >using functional MRI." It is the first unequivocal demonstration that the
signal that "everybody measures to understand how the brain works with fMRI in
fact reflects neuronal activity."<

3. >The iron in blood haemoglobin is a superb inherent magnetic
susceptibility-induced T2*-shortening intravascular contrast agent found in
every tissue. 
It is therefore used as a local indicator of functional activation 
because oxygenated arterial blood contains oxygenated haemoglobin, which is
diamagnetic and has a small magnetic susceptibility effect. It does not,
therefore, significantly alter the regional magnetic field and does not greatly
affect tissue T2*. Deoxygenation of haemoglobin produces deoxyhaemoglobin, a
significantly more paramagnetic species of iron due to the four unpaired
electrons, and this species disturbs the local magnetic field, B0, in a region
of tissue leading to the large observed magnetic susceptibility effect.<



Is there no contradiction somewhere in them 3?

1. sounds like anearobic, 3. like deoxygenation is relevant
and 2 did not really seem to go into 1 and 3 together much it seemed ... But I
did not really bother to think that much along.





More information about the Neur-sci mailing list