title: Micro-endoscopic system for functional assessment of neural circuits in deep brain regions: Simultaneous optical and electrical recordings of auditory responses in mouse's inferior colliculus.
abstract: In vivo Ca2+imaging is a powerful method for the functional assessment of neural circuits. Although multi-photon excitation fluorescence microscopy has been widely used, observation of circuits in deep brain regions remains challenging. Recently, observing these deep regions has become possible via an endoscope consisting of an optical fiber bundle or gradient-index lens. We have designed a micro-endoscope system that enables simultaneous optical recording of fluorescence and electrical recording of neural activity. Using this system, we recorded auditory responses by simultaneously detecting changes in the fluorescence intensity of a Ca2+indicator dye, multi-unit activities (MUA), and local field potentials (LFP) in the mouse's inferior colliculus (IC). Such simultaneous optical and electrical recordings enabled detailed comparison of electrically recorded phenomena (MUA and LFP) and optically recorded Ca2+response. By systematically changing sound frequency and intensity, we determined the frequency tuning of the recording site. The best frequency shifted higher as the probe advanced more deeply, demonstrating that the system is capable of optically measuring the dorso-ventral organization of IC (i.e., tonotopicity). Thus, our new micro-endoscope system will be useful in the neurophysiological studies of a wide range of brain circuits, including those within the auditory system.
authors.affiliation: Graduate School of Life and Medical Sciences, Doshisha University, 1-3, Miyakodani, Tatara, Kyotanabe, Kyoto 610-0321, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Yashiro
authors.affiliation: Department of Systems Biology, Osaka Bioscience Institute, 6-2-4, Furuedai, Suita, Osaka 565-0874, Japan; Neuro Programming Research Co., Osaka 561-0883, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Nakahara
authors.affiliation: Graduate School of Life and Medical Sciences, Doshisha University, 1-3, Miyakodani, Tatara, Kyotanabe, Kyoto 610-0321, Japan; Department of Systems Biology, Osaka Bioscience Institute, 6-2-4, Furuedai, Suita, Osaka 565-0874, Japan; Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation, Kobe 650-0047, Japan; Center for Life Science and Technology, Kobe, Japan. Electronic address: kazuo.funabiki@riken.jp.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Funabiki
authors.affiliation: Graduate School of Life and Medical Sciences, Doshisha University, 1-3, Miyakodani, Tatara, Kyotanabe, Kyoto 610-0321, Japan; Shandong University, Jinan 250100, China. Electronic address: riquimaroux@gmail.com.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Riquimaroux
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping / Q000295:instrumentation* / Q000379:methods; D002118:Calcium / Q000378:metabolism; D007202:Indicators and Reagents / Q000378:metabolism; D007245:Inferior Colliculi / Q000166:cytology* / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D036641:Microscopy, Fluorescence, Multiphoton; D009434:Neural Pathways / Q000502:physiology*; D044582:Neuroendoscopes; D044583:Neuroendoscopy / Q000295:instrumentation*
chemical_list: D007202:Indicators and Reagents; D002118:Calcium
keywords: Fiber optics; In vivo Ca(2+) imaging; Local field potential; Multi-unit recording