Extraction of optical properties and prediction of light distribution in rat brain tissue

Mehdi Azimipour, Ryan Baumgartner, Yuming Liu, Steven Jacques, Kevin Eliceiri, Ramin Pashaie

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Predicting the distribution of light inside any turbid media, such as biological tissue, requires detailed information about the optical properties of the medium, including the absorption and scattering coefficients and the anisotropy factor. Particularly, in biophotonic applications where photons directly interact with the tissue, this information translates to system design optimization, precision in light delivery, and minimization of unintended consequences, such as phototoxicity or photobleaching. In recent years, optogenetics has opened up a new area in deep brain stimulation with light and the method is widely adapted by researchers for the study of the brain circuitries and the dynamics of neurological disorders. A key factor for a successful optogenetic stimulation is delivering an adequate amount of light to the targeted brain objects. The adequate amount of light needed to stimulate each brain object is identified by the tissue optical properties as well as the type of opsin expressed in the tissue, wavelength of the light, and the physical dimensions of the targeted area. Therefore, to implement a precise light delivery system for optogenetics, detailed information about the optical properties of the brain tissue and a mathematical model that incorporates all determining factors is needed to find a good estimation of light distribution in the brain. In general, three measurements are required to obtain the optical properties of any tissue, namely diffuse transmitted light, diffuse reflected light, and transmitted ballistic beam. In this report, these parameters were measured in vitro using intact rat brain slices of 500 ìm thickness via a two-integrating spheres optical setup. Then, an inverse adding doubling method was used to extract the optical properties of the tissue from the collected data. These experiments were repeated to cover the whole brain tissue with high spatial resolution for the three different cuts (transverse, sagittal, and coronal) and three different wavelengths (405, 532, and 635 nm) in the visible range of the spectrum. A three-dimensional atlas of the rat brain optical properties was constructed based on the experimental measurements. This database was linked to a Monte Carlo toolbox to simulate light distribution in the tissue for different light source configurations.

Original languageEnglish (US)
Article number075001
JournalJournal of Biomedical Optics
Volume19
Issue number7
DOIs
StatePublished - 2014

Fingerprint

rats
brain
Rats
Brain
Optical properties
Tissue
Light
optical properties
predictions
Optogenetics
stimulation
delivery
Phototoxic Dermatitis
Opsins
Photobleaching
Wavelength
design optimization
Deep Brain Stimulation
scattering coefficients
Atlases

Keywords

  • absorption coefficient
  • anisotropy factor
  • integrating sphere
  • inverse adding doubling
  • Monte Carlo simulation.
  • optogenetics
  • scattering coefficient

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biomaterials
  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Medicine(all)

Cite this

Azimipour, M., Baumgartner, R., Liu, Y., Jacques, S., Eliceiri, K., & Pashaie, R. (2014). Extraction of optical properties and prediction of light distribution in rat brain tissue. Journal of Biomedical Optics, 19(7), [075001]. https://doi.org/10.1117/1.JBO.19.7.075001

Extraction of optical properties and prediction of light distribution in rat brain tissue. / Azimipour, Mehdi; Baumgartner, Ryan; Liu, Yuming; Jacques, Steven; Eliceiri, Kevin; Pashaie, Ramin.

In: Journal of Biomedical Optics, Vol. 19, No. 7, 075001, 2014.

Research output: Contribution to journalArticle

Azimipour, M, Baumgartner, R, Liu, Y, Jacques, S, Eliceiri, K & Pashaie, R 2014, 'Extraction of optical properties and prediction of light distribution in rat brain tissue', Journal of Biomedical Optics, vol. 19, no. 7, 075001. https://doi.org/10.1117/1.JBO.19.7.075001
Azimipour, Mehdi ; Baumgartner, Ryan ; Liu, Yuming ; Jacques, Steven ; Eliceiri, Kevin ; Pashaie, Ramin. / Extraction of optical properties and prediction of light distribution in rat brain tissue. In: Journal of Biomedical Optics. 2014 ; Vol. 19, No. 7.
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