Resting-state Functional Ultrasound Imaging of Cerebral Blood Flow and Functional Connectivity Changes in Hibernating Mice.

Hibernation can significantly reduce energy consumption and prolong survival by decreasing the metabolic rate and body temperature. Understanding the brain regulatory mechanisms may help overcome challenges in applying hibernation techniques to humans. In this study, we induced hibernation-like state in mice using pharmacological agents and monitored the process within the brain using resting-state functional ultrasound imaging. During hibernation and recovery, we measured various physiological parameters, including heart rate, body temperature, and cerebral blood volume. Additionally, we observed cerebral hemodynamic metrics and brain functional connectivity (FC) patterns. The results revealed significant reductions in heart rate, body temperature, and cerebral blood volume during this state. Notably, cerebral blood flow (CBF) decreased by about 50% on average, with the thalamus showing a more pronounced and delayed decline compared to other examined regions, accompanied by corresponding alterations in FC. A strong correlation (r = 0.82) was observed between changes in CBF and brain FC. This study provides insights into the unique regulation of CBF during hibernation, offering a deeper understanding of the brain regulation in this process.