Systems and methods for use in measuring sympathetic nervous system activityor blood vessel autoregulation correctedfor sympathetic activity. The choroid plexus in the human eye is imaged and,using the resulting image, the vascular perfusion density(VPD) in the choroid is measured. VPD provides a measurement that is directlyrelated to sympathetic nervous system activity. Theeffect of stimuli on sympathetic nervous system activity can be measured bycomparing pre-stimuli VPD measurements with post-stimulimeasurements. Quantifying VPD can be performed by determining pixel densitywithin specific areas of the choroid plexusimage. Altered sympathetic nervous system activity can be detected in asubject by comparing that subject's VPD measurements tobaseline VPD measurements from healthy individuals. Blood vesselautoregulation can be measured by imaging changes in other bloodvessels in the eye and correcting with choroid VPD measurements of sympatheticactivity.
