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Two-photon excited fluorescence microscopy has emerged as a powerful tool to study synaptic, cellular and integrative processes. IntroductionĪdvances in deep tissue optical microscopy have been a driving force in biology and neuroscience. From measurements on neural tissues and complementary simulations, we find that strong forward scattering in biological tissues can enhance the memory effect range and thus the possible field-of-view by more than an order of magnitude compared to isotropic scattering for ∼1 mm thick tissue layers. But those correlations (‘angular memory effect’) are of a very short range and should theoretically be only present behind and not inside scattering media. Recently developed techniques use scattered photons for imaging by exploiting angular correlations in transmitted light and could potentially increase imaging depths. High resolution optical microscopy is essential in neuroscience but suffers from scattering in biological tissues and therefore grants access to superficial brain layers only.
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