  Despite great progress in neuroscience, there are still fundamental
unanswered questions about the brain, including the origin of subjective
experience and consciousness. Some answers might rely on new physical
mechanisms. Given that biophotons have been discovered in the brain, it is
interesting to explore if neurons use photonic communication in addition to the
well-studied electro-chemical signals. Such photonic communication in the brain
would require waveguides. Here we review recent work [S. Kumar, K. Boone, J.
Tuszynski, P. Barclay, and C. Simon, Scientific Reports 6, 36508 (2016)]
suggesting that myelinated axons could serve as photonic waveguides. The light
transmission in the myelinated axon was modeled, taking into account its
realistic imperfections, and experiments were proposed both in-vivo and
in-vitro to test this hypothesis. Potential implications for quantum biology
are discussed.
