Resting-state functional connectivity analysis of the mouse brain using intrinsic optical signal imaging of cerebral blood volume dynamics

Objective: Resting-state functional connectivity (rsFC) of the human brain is closely related with neurological and psychiatric disorders. Mice are widely used to investigate the physiological mechanisms of such disorders, because of the applicability of invasive experimental techniques. Thus, studies on rsFC of the mouse brain are essential to link physiological mechanisms with these disorders in humans. In this study, we investigated the applicability of intrinsic optical signal imaging of cerebral blood volume (IOSI-CBV) for rsFC analysis of the mouse brain. Approach: Transcranial IOSI-CBV images were collected from the brains of un-anesthetized wild-type mice with a cooled-CCD camera. The time traces of all pixels were averaged to create a global signal (GS). Marginal and partial correlation analyses were performed to estimate the rsFC based on CBV signals both with and without GS removal. The consistency of the results were confirmed by comparing them with to the rsFCs data reported in the previous studies. Main results: We confirmed that GS correlated with heart rate fluctuation in the FC frequency band. The marginal correlation coefficient of CBV with GS removal was consistent with measurements using conventional optical imaging methods relying on oxygenated hemoglobin concentration and cerebral blood flow. Significance: These results suggest the applicability and usefulness of the transcranial IOSI-CBV method to estimate rsFC of the mouse brain.