Acetazolamide Blocks Increase in fc-fMRI Global Signal in Hypoxia, While Increasing Default Mode Network Correlations

Kang Wang¹, Zachary M. Smith¹, Chi Wah Wong¹, David J. Dubowitz¹

High altitude hypoxia increases CMRO2, CBF, and OEF. We investigated how this might impact BOLD functional connectivity. 5 subjects were studied during normoxia, and following 2-days sustained hypoxia with and without acetazolamide prophylaxis (a treatment for high altitude hypoxia symptoms). Hypoxia increased overall correlations with posterior cingulated cortex, and the global signal amplitude. Acetazolamide mitigated these global effects, while increasing correlations in the default mode network. CO2 has been implicated as a modulator of BOLD functional connectivity, but during hypoxia this does not seem to be the sole contributor. Alterations in CBF, CMRO2 and neuronal activity must also be considered.