title: Coding of stimulus strength via analog calcium signals in Purkinje cell dendrites of awake mice.
abstract: The climbing fiber input to Purkinje cells acts as a teaching signal by triggering a massive influx of dendritic calcium that marks the occurrence of instructive stimuli during cerebellar learning. Here, we challenge the view that these calcium spikes are all-or-none and only signal whether the instructive stimulus has occurred, without providing parametric information about its features. We imaged ensembles of Purkinje cell dendrites in awake mice and measured their calcium responses to periocular airpuffs that serve as instructive stimuli during cerebellar-dependent eyeblink conditioning. Information about airpuff duration and pressure was encoded probabilistically across repeated trials, and in two additional signals in single trials: the synchrony of calcium spikes in the Purkinje cell population, and the amplitude of the calcium spikes, which was modulated by a non-climbing fiber pathway. These results indicate that calcium-based teaching signals in Purkinje cells contain analog information that encodes the strength of instructive stimuli trial-by-trial.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, United States.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Najafi
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, United States Princeton Neuroscience Institute, Princeton University, Princeton, United States.
authors.forename: Andrea
authors.initials: A
authors.lastname: Giovannucci
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, United States Princeton Neuroscience Institute, Princeton University, Princeton, United States.
authors.forename: Samuel S-H
authors.initials: SS
authors.lastname: Wang
authors.affiliation: Department of Psychology, University of Pennsylvania, Philadelphia, United States jmed@psych.upenn.edu.
authors.forename: Javier F
authors.initials: JF
authors.lastname: Medina
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001767:Blinking / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D002531:Cerebellum / Q000166:cytology / Q000502:physiology; D003215:Conditioning, Eyelid / Q000502:physiology; D003712:Dendrites / Q000502:physiology*; D005260:Female; D008810:Mice, Inbred C57BL; D036641:Microscopy, Fluorescence, Multiphoton; D009412:Nerve Fibers / Q000502:physiology; D010812:Physical Stimulation; D011689:Purkinje Cells / Q000166:cytology / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*
chemical_list: D002118:Calcium
keywords: cerebellum; climbing fiber; motor learning; neural coding; plasticity; unconditioned stimulus