Measurement of the optical properties of rat brain tissue using contact spatially resolved spectroscopy

摘要

Nowadays, biophotonics is widely used in neuroscience. The effectiveness of biophotonic techniques, such as fluorescence imaging and optogenetics, is affected by the optical properties of the examined tissue. Therefore, knowledge of these properties is essential to carefully plan experiments. Mice and rats are widely used in neuroscience studies. However, reports about optical properties of their brains are very rare. We measured optical absorption μ_a and reduced scattering μ'_s coefficients of native rat brain in the visible and near-infrared wavelength region, using contact spatially resolved spectroscopy (SRS). In this study, we estimate μ_a and μ'_s for the rat cortex and discuss their stability in time. Additionally, variations in optical properties within and between samples were characterized. The results extend the range of known optical properties for the rat cortex, especially in the visible range, relevant to optogenetics. μ_a and μ'_s are stable within a time span of four hours, and show low variation in and between brain samples. This indicates that a suitable protocol was used to estimate optical properties of rodent brain tissue. Since contact SRS is a non-destructive method, this technique could be used also to measure μ_a and μ'_s in living animals. Moreover, the probe has small dimensions, allowing the characterization of optical properties in different structures of the brain.