Functional imaging through scattering medium via fluorescence speckle demixing and localization

Recently, fluorescence-based optical techniques have emerged as a powerful tool to probe information in the mammalian brain. However, tissue heterogeneities prevent clear imaging of deep neuron bodies due to light scattering. While several up-to-date approaches based on ballistic light allow to retrieve information at shallow depths inside the brain, non-invasive localization and functional imaging at depth still remains a challenge. It was recently shown that functional signals from time-varying fluorescent emitters located behind scattering samples could be retrieved by using a matrix factorization algorithm. Here we show that the seemingly information-less, low-contrast fluorescent speckle patterns recovered by the algorithm can be used to locate each individual emitter, even in the presence of background fluorescence. We test our approach by imaging the temporal activity of large groups of fluorescent sources behind different scattering phantoms mimicking biological tissues, and through a brain slice with a thickness of & SIM;200 & mu;m.

Automated summary

Recently, fluorescence-based optical techniques have been used to probe information in the mammalian brain, but light scattering from tissue heterogeneities hinders clear imaging of deep neuron bodies. While some approaches allow shallow-depth retrieval of information, non-invasive localization and functional imaging at depth remains challenging. A matrix factorization algorithm has been shown to retrieve functional signals from fluorescent emitters behind scattering samples, and in this study, it is demonstrated that low-contrast fluorescent speckle patterns recovered by the algorithm can be used to locate individual emitters, even in the presence of background fluorescence. The approach is tested on different scattering phantoms and a brain slice.