An Optical Implant for Parkinson\u2019s disease Monitoring using Substantia Nigra Reflectance properties

Objective: We present an optical implant as an innovative tool for assessing brain tissue reflectance to monitor the progression of Parkinson\u2019s disease (PD). Methods: We first determined the wavelength that maximized optical discrimination between tissues reflectance for both fixed and living brain samples, enabling the identification of the affected brain region, the Substantia Nigra pars compacta (SN), from surrounding areas. Based on this analysis, we developed a monochromatic intracranial implant capable of autonomously recording in vivo tissue reflectance throughout disease progression. Results: in vivo studies in pig brains enabled the determination of the specific optical properties of the SN, whereas the midbrain organoid model of PD revealed their temporal alterations. Conclusion: Spatial analyses revealed significant differences in both polychromatic and monochromatic light reflectance between the SN and other brain regions. Temporal studies demonstrated precise recording capabilities in a PD organoid model. Significance: These results in vitro and in vivo support the reliability and suitability of the monitoring implant for use in preclinical models of PD, laying the groundwork for future clinical applications.