title: Neurons are recruited to a memory trace based on relative neuronal excitability immediately before training.
abstract: Memories are thought to be sparsely encoded in neuronal networks, but little is known about why a given neuron is recruited or allocated to a particular memory trace. Previous research shows that in the lateral amygdala (LA), neurons with increased CREB are selectively recruited to a fear memory trace. CREB is a ubiquitous transcription factor implicated in many cellular processes. Which process mediates neuronal memory allocation? One hypothesis is that CREB increases neuronal excitability to bias neuronal recruitment, although this has not been shown experimentally. Here we use several methods to increase neuronal excitability and show this both biases recruitment into the memory trace and enhances memory formation. Moreover, artificial activation of these neurons alone is a sufficient retrieval cue for fear memory expression, showing that these neurons are critical components of the memory trace. These results indicate that neuronal memory allocation is based on relative neuronal excitability immediately before training.
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Adelaide P
authors.initials: AP
authors.lastname: Yiu
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Valentina
authors.initials: V
authors.lastname: Mercaldo
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Chen
authors.initials: C
authors.lastname: Yan
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada.
authors.forename: Blake
authors.initials: B
authors.lastname: Richards
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Asim J
authors.initials: AJ
authors.lastname: Rashid
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Hwa-Lin Liz
authors.initials: HL
authors.lastname: Hsiang
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Jessica
authors.initials: J
authors.lastname: Pressey
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Vivek
authors.initials: V
authors.lastname: Mahadevan
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Tran
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychiatry, Erasmus Medical Center, 3000 CA Rotterdam, the Netherlands.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Kushner
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Woodin
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Frankland
authors.affiliation: Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada. Electronic address: sheena.josselyn@sickkids.ca.
authors.forename: Sheena A
authors.initials: SA
authors.lastname: Josselyn
mesh_terms: D000679:Amygdala / Q000502:physiology; D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D005239:Fear / Q000502:physiology*; D005260:Female; D007858:Learning; D008297:Male; D008568:Memory / Q000502:physiology*; D009424:Nervous System Physiological Phenomena; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000378:metabolism / Q000502:physiology*
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein