A technique to ensure correct color stimulation by functional MRI to study in vivo the human melanopsin ganglion cells system

This paper describes a methodology to achieve correct light radiation coloring for stimulating intrinsically photosensitive melanopsin retinal ganglion cells. Indeed, it has been shown that light is capable of causing a response from the master circadian pacemaker located in the suprachiasmatic nucleus of the hypothalamus. A study was conducted in an experimental set-up using a high field clinic Magnetic Resonance scanner equipped with a stereoscopic viewer capable of projecting specific wavelengths to stimulate melanopsin retinal system. Subjects were monitored by acquiring Functional Magnetic Resonance Imaging, observing the response in subcortical (i.e., hypothalamus) and limbic areas (i.e., amygdala) and in some cortical areas primarily related to alertness. The spectral radiation emitted by the viewer was measured with laboratory instruments, and some considerations were also made on its possible influence at the level of the circadian cycle.