Abstract #2134
Changes in CBF/CMRO 2 coupling with graded visual stimuli are modulated by baseline perfusion
Joseph Whittaker 1 , Ian Driver 1 , Molly Bright 1 , and Kevin Murphy 1
1
CUBRIC, School of Psychology, Cardiff
University, Cardiff, United Kingdom
The BOLD fMRI response depends on multiple physiological
factors, in particular, the ratio of fractional changes
in CBF and CMRO2, defined as n. Meaningful comparisons
of BOLD responses between stimulus conditions rely upon
a constant n, which may not be the case. The BOLD and
CBF responses to 4 visual contrast levels were measured
in 9 subjects during normocapnia and hypercapnia. We
found larger BOLD responses during hypercapnia,
suggesting altered CBF/CMRO2 coupling dynamics. These
data show BOLD changes that are consistent with varying
n values across contrast, and which are modulated
further by changes in baseline physiology.
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