Impact of cerebral blood flow level on the fluctuations of resting-state BOLD fMRI in anesthetized rats

International audienceThe Blood Oxygen Level Dependent (BOLD) signal, used in resting-state functional Magnetic Resonance Imaging (fMRI), is tighly linked to Cerebral Blood Flow (CBF). This study evaluates the impact of the CBF on the low-frequencies BOLD fluctuations and four physiological parameters during resting state in 5 groups of rats (Wistar and Long-Evans) anesthetized with Isoflurane, Medetomidine, Etomidate and Urethane. It is shown that the CBF is not related to physiological parameters, and there exists a range of CBF values where the BOLD fluctations are sufficiently high for being used in any other analysis

Functional connectivity is preserved but reorganized across several anesthetic regimes

International audienceUnder anesthesia, systemic variables and CBF are modified. How does this alter the connectivity measures obtained with rs-fMRI? To tackle this question, we explored the effect of four different anesthetics on Long Evans and Wistar rats with multimodal recordings of rs-fMRI, systemic variables and CBF. After multimodal signal processing, we show that the blood-oxygen-level-dependent (BOLD) variations and functional connectivity (FC) evaluated at low frequencies (0.031-0.25 Hz) do not depend on systemic variables and are preserved across a large interval of baseline CBF values. Based on these findings, we found that most brain areas remain functionally active under any anesthetics, i.e. connected to at least one other brain area, as shown by the connectivity graphs. In addition, we quantified the influence of nodes by a measure of functional connectivity strength to show the specific areas targeted by anesthetics and compare correlation values of edges at different levels. These measures enable us to highlight the specific network alterations induced by anesthetics. Altogether, this suggests that changes in connectivity could be evaluated under anesthesia, routinely used in the control of neurological injury

Relationship between serotypes, disease characteristics and 30-day mortality in adults with invasive pneumococcal disease

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