title: Long-range orbitofrontal and amygdala axons show divergent patterns of maturation in the frontal cortex across adolescence.
abstract: The adolescent transition from juvenile to adult is marked by anatomical and functional remodeling of brain networks. Currently, the cellular and synaptic level changes underlying the adolescent transition are only coarsely understood. Here, we use two-photon imaging to make time-lapse observations of long-range axons that innervate the frontal cortex in the living brain. We labeled cells in the orbitofrontal cortex (OFC) and basolateral amygdala (BLA) and imaged their axonal afferents to the dorsomedial prefrontal cortex (dmPFC). We also imaged the apical dendrites of dmPFC pyramidal neurons. Images were taken daily in separate cohorts of juvenile (P24-P28) and young adult mice (P64-P68), ages where we have previously discovered differences in dmPFC dependent decision-making. Dendritic spines were pruned across this peri-adolescent period, while BLA and OFC afferents followed alternate developmental trajectories. OFC boutons showed no decrease in density, but did show a decrease in daily bouton gain and loss with age. BLA axons showed an increase in both bouton density and daily bouton gain at the later age, suggesting a delayed window of enhanced plasticity. Our findings reveal projection specific maturation of synaptic structures within a single frontal region and suggest that stabilization is a more general characteristic of maturation than pruning.
authors.affiliation: Neuroscience Graduate Program, University of California, San Francisco, CA 94158, United States; Psychology Department, University of California, Berkeley, CA 94720, United States; Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, United States.
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Johnson
authors.affiliation: Neuroscience Graduate Program, University of California, San Francisco, CA 94158, United States.
authors.forename: F Alexandra
authors.initials: FA
authors.lastname: Loucks
authors.affiliation: Psychology Department, University of California, Berkeley, CA 94720, United States.
authors.forename: Hannah
authors.initials: H
authors.lastname: Peckler
authors.affiliation: Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, United States.
authors.forename: A Wren
authors.initials: AW
authors.lastname: Thomas
authors.affiliation: Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, United States.
authors.forename: Patricia H
authors.initials: PH
authors.lastname: Janak
authors.affiliation: Psychology Department, University of California, Berkeley, CA 94720, United States; Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, United States. Electronic address: wilbrecht@berkeley.edu.
authors.forename: Linda
authors.initials: L
authors.lastname: Wilbrecht
mesh_terms: D000344:Afferent Pathways; D000375:Aging; D000679:Amygdala / Q000166:cytology*; D000818:Animals; D001369:Axons / Q000502:physiology*; D003712:Dendrites / Q000502:physiology; D008297:Male; D051379:Mice; D009473:Neuronal Plasticity; D017397:Prefrontal Cortex / Q000166:cytology*; D017966:Pyramidal Cells / Q000166:cytology; D012741:Sexual Maturation
keywords: Axonal bouton; Dendritic spine; Development; Pruning; Structural plasticity; Two-photon microscopy