Optical measurement of microvascular oxygenation and blood flow responses in awake mouse cortex during functional activation. Issue 3 (March 2022)

• Record Type: Journal Article
• Authors: Şencan, İkbal; Esipova, Tatiana; Kılıç, Kıvılcım; Li, Baoqiang; Desjardins, Michèle; Yaseen, Mohammad A; Wang, Hui; Porter, Jason E; Kura, Sreekanth; Fu, Buyin; Secomb, Timothy W; Boas, David A; Vinogradov, Sergei A; Devor, Anna; Sakadžić, Sava
• Is Part Of: Journal of cerebral blood flow & metabolism. Volume 42:Issue 3(2022)
• Page Start: 510
• Page End: 525
• Publication Date: 2022-03
• Subjects: Intravascular partial pressure of oxygen -- cortical layers -- neurovascular coupling -- oxygen extraction fraction -- two-photon microscopy; Cerebral circulation -- Periodicals; Brain -- Metabolism -- Periodicals; Brain -- Blood-vessels -- Periodicals; Cerebrovascular disease -- Periodicals; 612.824
• DOI: 10.1177/0271678X20928011
• Languages: English
• ISSNs: 0271-678X

Abstract

The cerebral cortex has a number of conserved morphological and functional characteristics across brain regions and species. Among them, the laminar differences in microvascular density and mitochondrial cytochrome c oxidase staining suggest potential laminar variability in the baseline O2 metabolism and/or laminar variability in both O2 demand and hemodynamic response. Here, we investigate the laminar profile of stimulus-induced intravascular partial pressure of O2 (pO2) transients to stimulus-induced neuronal activation in fully awake mice using two-photon phosphorescence lifetime microscopy. Our results demonstrate that stimulus-induced changes in intravascular pO2 are conserved across cortical layers I–IV, suggesting a tightly controlled neurovascular response to provide adequate O2 supply across cortical depth. In addition, we observed a larger change in venular O2 saturation (ΔsO2 ) compared to arterioles, a gradual increase in venular ΔsO2 response towards the cortical surface, and absence of the intravascular "initial dip" previously reported under anesthesia. This study paves the way for quantification of layer-specific cerebral O2 metabolic responses, facilitating investigation of brain energetics in health and disease and informed interpretation of laminar blood oxygen level dependent functional magnetic resonance imaging signals.