Nogo receptor 1 limits tactile task performance independent of basal anatomical plasticity.
The genes that govern how experience refines neural circuitry and alters synaptic structural plasticity are poorly understood. The nogo-66 receptor 1 gene (ngr1) is one candidate that may restrict the rate of learning as well as basal anatomical plasticity in adult cerebral cortex. To investigate if ngr1 limits the rate of learning we tested adult ngr1 null mice on a tactile learning task. Ngr1 mutants display greater overall performance despite a normal rate of improvement on the gap-cross assay, a whisker-dependent learning paradigm. To determine if ngr1 restricts basal anatomical plasticity in the associated sensory cortex, we repeatedly imaged dendritic spines and axonal varicosities of both constitutive and conditional adult ngr1 mutant mice in somatosensory barrel cortex for two weeks through cranial windows with two-photon chronic in vivo imaging. Neither constant nor acute deletion of ngr1 affected turnover or stability of dendritic spines or axonal boutons. The improved performance on the gap-cross task is not attributable to greater motor coordination, as ngr1 mutant mice possess a mild deficit in overall performance and a normal learning rate on the rotarod, a motor task. Mice lacking ngr1 also exhibit normal induction of tone-associated fear conditioning yet accelerated fear extinction and impaired consolidation. Thus, ngr1 alters tactile and motor task performance but does not appear to limit the rate of tactile or motor learning, nor determine the low set point for synaptic turnover in sensory cortex.
Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, United States of America.
Jennifer I
JI
Park
Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, United States of America.
Michael G
MG
Frantz
Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, United States of America.
Ryan J
RJ
Kast
Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, United States of America.
Katherine S
KS
Chapman
Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, United States of America.
Hilary M
HM
Dorton
Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, United States of America.
Céleste-Élise
CÉ
Stephany
Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, United States of America.
Megan T
MT
Arnett
Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, United States of America.
David H
DH
Herman
Developmental Neuroscience Program, Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, United States of America.
Aaron W
AW
McGee
D000818:Animals; D001369:Axons / Q000502:physiology; D049229:Dendritic Spines / Q000502:physiology; D005260:Female; D058851:GPI-Linked Proteins / Q000235:genetics / Q000378:metabolism; D007858:Learning; D008297:Male; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods; D009185:Myelin Proteins / Q000235:genetics* / Q000378:metabolism; D009473:Neuronal Plasticity / Q000235:genetics*; D000070816:Nogo Receptor 1; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D045442:Rotarod Performance Test; D013003:Somatosensory Cortex / Q000502:physiology; D013647:Task Performance and Analysis
D058851:GPI-Linked Proteins; D009185:Myelin Proteins; D000070816:Nogo Receptor 1; C486580:RTN4R protein, human; D011956:Receptors, Cell Surface