title: Roadmap on neurophotonics.
abstract: Mechanistic understanding of how the brain gives rise to complex behavioral and cognitive functions is one of science's grand challenges. The technical challenges that we face as we attempt to gain a systems-level understanding of the brain are manifold. The brain's structural complexity requires us to push the limit of imaging resolution and depth, while being able to cover large areas, resulting in enormous data acquisition and processing needs. Furthermore, it is necessary to detect functional activities and 'map' them onto the structural features. The functional activity occurs at multiple levels, using electrical and chemical signals. Certain electrical signals are only decipherable with sub-millisecond timescale resolution, while other modes of signals occur in minutes to hours. For these reasons, there is a wide consensus that new tools are necessary to undertake this daunting task. Optical techniques, due to their versatile and scalable nature, have great potentials to answer these challenges. Optical microscopy can now image beyond the diffraction limit, record multiple types of brain activity, and trace structural features across large areas of tissue. Genetically encoded molecular tools opened doors to controlling and detecting neural activity using light in specific cell types within the intact brain. Novel sample preparation methods that reduce light scattering have been developed, allowing whole brain imaging in rodent models. Adaptive optical methods have the potential to resolve images from deep brain regions. In this roadmap article, we showcase a few major advances in this area, survey the current challenges, and identify potential future needs that may be used as a guideline for the next steps to be taken.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Institute for Systems Genomics, University of Connecticut, 191 Auditorium Rd, Storrs, CT 06269-3222, USA.
authors.forename: Yong Ku
authors.initials: YK
authors.lastname: Cho
authors.affiliation: Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA.
authors.forename: Guoan
authors.initials: G
authors.lastname: Zheng
authors.affiliation: Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Singapore 637553, Singapore.
authors.forename: George J
authors.initials: GJ
authors.lastname: Augustine
authors.affiliation: Departments of Chemistry and Chemical Biology and Physics, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hochbaum
authors.affiliation: Departments of Chemistry and Chemical Biology and Physics, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Howard Hughes Medical Institute, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Cohen
authors.affiliation: Division of Brain Sciences, Department of Medicine, Imperial College London, London W12 0NN, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Knöpfel
authors.affiliation: Istituto Italiano di Tecnologia (IIT), Center for Biomolecular Nanotechnologies, Via Barsanti sn, I-73010 Arnesano (Lecce), Italy.
authors.forename: Ferruccio
authors.initials: F
authors.lastname: Pisanello
authors.affiliation: European Laboratory for Non Linear Spectroscopy, University of Florence, Via N. Carrara 1, I-50019 Sesto Fiorentino (FI), Italy; Department of Physics, University of Florence, Via G. Sansone 1, I-50019 Sesto Fiorentino, Italy; Istituto Nazionale di Ottica, L.go E. fermi 2, I-50100 Firenze, Italy.
authors.forename: Francesco S
authors.initials: FS
authors.lastname: Pavone
authors.affiliation: Biomedical Photonic Imaging group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Ivo M
authors.initials: IM
authors.lastname: Vellekoop
authors.affiliation: Centre for Neural Circuits and Behaviour, University of Oxford, Mansfield Road, Oxford OX1 3SR, UK; Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Booth
authors.affiliation: Department of Biomedical Engineering, University of Virginia, 415 Lane Road, Charlottesville, VA 22908, USA.
authors.forename: Song
authors.initials: S
authors.lastname: Hu
authors.affiliation: Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road East, Irvine, CA 92617, USA.
authors.forename: Jiang
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road East, Irvine, CA 92617, USA.
authors.forename: Zhongping
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Biomedical Optics, Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hoshi
keywords: biophotonics; brain; imaging; microscopy; neurophotonics; neuroscience; spectroscopy