title: Simple platform for chronic imaging of hippocampal activity during spontaneous behaviour in an awake mouse.
abstract: Chronic electrophysiological recordings of neuronal activity combined with two-photon Ca2+imaging give access to high resolution and cellular specificity. In addition, awake drug-free experimentation is required for investigating the physiological mechanisms that operate in the brain. Here, we developed a simple head fixation platform, which allows simultaneous chronic imaging and electrophysiological recordings to be obtained from the hippocampus of awake mice. We performed quantitative analyses of spontaneous animal behaviour, the associated network states and the cellular activities in the dorsal hippocampus as well as estimated the brain stability limits to image dendritic processes and individual axonal boutons. Ca2+imaging recordings revealed a relatively stereotyped hippocampal activity despite a high inter-animal and inter-day variability in the mouse behavior. In addition to quiet state and locomotion behavioural patterns, the platform allowed the reliable detection of walking steps and fine speed variations. The brain motion during locomotion was limited to ~1.8 μm, thus allowing for imaging of small sub-cellular structures to be performed in parallel with recordings of network and behavioural states. This simple device extends the drug-free experimentation in vivo, enabling high-stability optophysiological experiments with single-bouton resolution in the mouse awake brain.
authors.affiliation: Neuroscience Axis, CHU de Québec Research Center (CHUL), Laval University, Québec, PQ, G1V 4G2, Canada.|Department of Biochemistry, Microbiology and Bio-informatics, Laval University, Québec, PQ, G1V 0A6, Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Villette
authors.affiliation: Department of Electrical and Computer Engineering, Laval University, Québec, PQ, G1V 0A6, Canada.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Levesque
authors.affiliation: Department of Electrical and Computer Engineering, Laval University, Québec, PQ, G1V 0A6, Canada.
authors.forename: Amine
authors.initials: A
authors.lastname: Miled
authors.affiliation: Department of Electrical and Computer Engineering, Laval University, Québec, PQ, G1V 0A6, Canada.
authors.forename: Benoit
authors.initials: B
authors.lastname: Gosselin
authors.affiliation: Neuroscience Axis, CHU de Québec Research Center (CHUL), Laval University, Québec, PQ, G1V 4G2, Canada.|Department of Biochemistry, Microbiology and Bio-informatics, Laval University, Québec, PQ, G1V 0A6, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Topolnik
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D001522:Behavior, Animal; D002118:Calcium / Q000378:metabolism; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D004567:Electrodes, Implanted; D004867:Equipment Design; D006257:Head; D006624:Hippocampus / Q000000981:diagnostic imaging* / Q000502:physiology / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D007103:Immobilization / Q000295:instrumentation / Q000379:methods*; D008124:Locomotion; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D036641:Microscopy, Fluorescence, Multiphoton / Q000295:instrumentation / Q000379:methods*; D057054:Molecular Imaging / Q000295:instrumentation / Q000379:methods*; D017729:Presynaptic Terminals / Q000502:physiology; D013702:Temporal Lobe / Q000000981:diagnostic imaging* / Q000502:physiology / Q000648:ultrastructure; D014851:Wakefulness / Q000502:physiology*
chemical_list: D002118:Calcium