title: Simultaneous recording of fluorescence and electrical signals by photometric patch electrode in deep brain regions in vivo.
abstract: Despite its widespread use, high-resolution imaging with multiphoton microscopy to record neuronal signals in vivo is limited to the surface of brain tissue because of limited light penetration. Moreover, most imaging studies do not simultaneously record electrical neural activity, which is, however, crucial to understanding brain function. Accordingly, we developed a photometric patch electrode (PME) to overcome the depth limitation of optical measurements and also enable the simultaneous recording of neural electrical responses in deep brain regions. The PME recoding system uses a patch electrode to excite a fluorescent dye and to measure the fluorescence signal as a light guide, to record electrical signal, and to apply chemicals to the recorded cells locally. The optical signal was analyzed by either a spectrometer of high light sensitivity or a photomultiplier tube depending on the kinetics of the responses. We used the PME in Oregon Green BAPTA-1 AM-loaded avian auditory nuclei in vivo to monitor calcium signals and electrical responses. We demonstrated distinct response patterns in three different nuclei of the ascending auditory pathway. On acoustic stimulation, a robust calcium fluorescence response occurred in auditory cortex (field L) neurons that outlasted the electrical response. In the auditory midbrain (inferior colliculus), both responses were transient. In the brain-stem cochlear nucleus magnocellularis, calcium response seemed to be effectively suppressed by the activity of metabotropic glutamate receptors. In conclusion, the PME provides a powerful tool to study brain function in vivo at a tissue depth inaccessible to conventional imaging devices.
authors.affiliation: Department of Neurobiology and Physiology, Faculty of Medicine, Kyoto University, Kyoto, Kyoto, Japan; and Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Kyoto, Japan.
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Hirai
authors.affiliation: Department of Neurobiology and Physiology, Faculty of Medicine, Kyoto University, Kyoto, Kyoto, Japan; and.
authors.forename: Eri
authors.initials: E
authors.lastname: Nishino
authors.affiliation: Department of Neurobiology and Physiology, Faculty of Medicine, Kyoto University, Kyoto, Kyoto, Japan; and ohmori@nbiol.med.kyoto-u.ac.jp.
authors.forename: Harunori
authors.initials: H
authors.lastname: Ohmori
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000161:Acoustic Stimulation; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D001306:Auditory Pathways / Q000502:physiology; D001921:Brain / Q000166:cytology* / Q000502:physiology*; D001931:Brain Mapping; D002118:Calcium / Q000378:metabolism; D002645:Chickens; D004558:Electric Stimulation; D005453:Fluorescence; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010783:Photometry; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011724:Pyridazines / Q000494:pharmacology; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014162:Transfection
chemical_list: D018756:GABA Antagonists; D026902:Potassium Channel Blockers; D011724:Pyridazines; D013757:Tetraethylammonium Compounds; C049853:gabazine; D015761:4-Aminopyridine; D002118:Calcium
keywords: acoustic local responses; brain activity in vivo; fluorescence calcium signal; local field electrical responses; photometric patch electrode