title: Beta2 oscillations (23-30 Hz) in the mouse hippocampus during novel object recognition.
abstract: The oscillatory activity of hippocampal neuronal networks is believed to play a role in memory acquisition and consolidation. Particular focus has been given to characterising theta (4-12 Hz), gamma (40-100 Hz) and ripple (150-250 Hz) oscillations. Beyond these well-described network states, few studies have investigated hippocampal beta2 (23-30 Hz) activity in vivo and its link to behaviour. A previous sudy showed that the exploration of novel environments may lead to the appearance of beta2 oscillations in the mouse hippocampus. In the present study we characterised hippocampal beta2 oscillations in mice during an object recognition task. We found prominent bursts of beta2 oscillations in the beginning of novel exploration sessions (four new objects), which could be readily observed by spectral analysis and visual inspection of local field potentials. Beta2 modulated hippocampal but not neocortical neurons and its power decreased along the session. We also found increased beta2 power in the beginning of a second exploration session performed 24 h later in a slightly modified environment (two new, two familiar objects), but to a lesser extent than in the first session. However, the increase in beta2 power in the second exploration session became similar to the first session when we pharmacologically impaired object recognition in a new set of experiments performed 1 week later. Our results suggest that hippocampal beta2 activity is associated with a dynamic network state tuned for novelty detection and which may allow new learning to occur.
authors.affiliation: Brain Institute, Federal University of Rio Grande do Norte, Natal, RN 59056-450, Brazil; Edmond and Lily Safra International Institute of Neuroscience of Natal, Natal, Brazil.
authors.forename: Arthur S C
authors.initials: AS
authors.lastname: França
authors.forename: George C
authors.initials: GC
authors.lastname: do Nascimento
authors.forename: Vítor
authors.initials: V
authors.lastname: Lopes-dos-Santos
authors.forename: Larissa
authors.initials: L
authors.lastname: Muratori
authors.forename: Sidarta
authors.initials: S
authors.lastname: Ribeiro
authors.forename: Bruno
authors.initials: B
authors.lastname: Lobão-Soares
authors.forename: Adriano B L
authors.initials: AB
authors.lastname: Tort
mesh_terms: D000818:Animals; D001611:Beta Rhythm / Q000187:drug effects / Q000502:physiology*; D004567:Electrodes, Implanted; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology; D006220:Haloperidol / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008569:Memory Disorders / Q000139:chemically induced / Q000503:physiopathology; D008810:Mice, Inbred C57BL; D009044:Motor Cortex / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009483:Neuropsychological Tests; D011619:Psychotropic Drugs / Q000494:pharmacology; D021641:Recognition, Psychology / Q000187:drug effects / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology; D013028:Space Perception / Q000187:drug effects / Q000502:physiology; D013826:Theta Rhythm / Q000502:physiology
chemical_list: D011619:Psychotropic Drugs; D006220:Haloperidol
keywords: brain rhythms; in vivo electrophysiology; local field potential; novelty; spectral analysis