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Julie Lefebvre

Title: Senior Scientist, Neurosciences & Mental Health
Designations: PhD
Phone: 416-813-7654 ext. 309248
Alternate Contact Name: Delina Romano
Alternate Phone: 416-813-7654 ext. 302400
Alternate Email:
U of T Positions: Assistant Professor, Department of Molecular Genetics
Chair Positions: Canada Research Chair in Developmental Neural Circuitry


Dr. Julie Lefebvre is a Senior Scientist in the Neurosciences and Mental Health Program, and an Assistant Professor of Molecular Genetics at the University of TorontoShe earned her PhD in Cell and Molecular Biology at the University of Pennsylvania in Philadelphia in 2005and completed her postdoctoral training at Harvard UniversityShe joined the Hospital for Sick Children’s Research Institute in December 2013.


In the developing brain, billons of nerve cells are generated and precisely organized into circuits to drive complex functions such as sensations, locomotion, and language. Abnormal neuronal wiring occurring in early life can have debilitating and lifelong consequences on brain function, and are implicated in several neurodevelopmental disorders.

The research focus of the Lefebvre lab is to understand how nerve cells develop and wire up into neural circuits, and to identify molecules that guide the formation of these specific connectivity patterns. In particular, they are investigating developing inhibitory nerves in regions such as the retina, cortex and cerebellum that are critical for establishing a balance between excitation and inhibition. Inhibitory nerve cells are especially vulnerable to early life insults and are implicated in disorders such as epilepsy and autism spectrum disorders. They employ genetic tools and animal models to study neuronal development and gene function, cutting-edge microscopy to resolve brain wiring with single cell resolution, molecular profiling, and computational analyses. This research is motivated by the goal to better understand how neural circuits develop in the healthy brain, and identify genetic and developmental alterations in circuits that underlie brain disorders.

Education and experience

  • 1999: B.Sc., McGill University, Montreal, QC
  • 2005: Ph.D., Cell and Molecular Biology, University of Pennsylvania, Philadelphia, PA, USA
  • 2005–2011: Postdoctoral Fellow, Harvard University, Cambridge MA
  • 2011–2013: Research Associate, Harvard University, Cambridge MA
  • 2013–2020: Scientist, Hospital for Sick Children
  • 2014–present: Assistant Professor, Department of Molecular Genetics, University of Toronto, Canada
  • 2020–present: Senior Scientist, Hospital for Sick Children


  • 2014–2019: Canada Research Chair in Neural Circuit Development, Tier 2
  • 2015: Sloan Research Fellowship in Neuroscience - Alfred P. Sloan Foundation
  • 2016: Summit Delegate, Japan’s 13th Annual Science, Technology & Society (STS) Forum, Kyoto, Japan
  • 2019–2024: Canada Research Chair in Neural Circuit Development, Renewal Tier 2


  1. Ing-Esteves S, Kostadinov D, Marocha J, Sing AD, Joseph KS, Laboulaye MA, Sanes JR, Lefebvre JL. Combinatorial Effects of Alpha- and Gamma-Protocadherins on Neuronal Survival and Dendritic Self-Avoidance. J Neurosci. 2018 03 14; 38(11):2713-2729. PMID: 29439167. 
  2. Lefebvre JL. Neuronal territory formation by the atypical cadherins and clustered protocadherinsSemin Cell Dev Biol. 2017 09; 69:111-121. PMID: 28756270. 
  3. Lefebvre JL, Sanes JR, Kay JN. Development of dendritic form and functionAnnu Rev Cell Dev Biol. 2015; 31:741-77. PMID: 26422333. 
  4. Lefebvre JL, Kostadinov D, Chen. WV, Maniatis T, Sanes JR. Protocadherins mediate dendritic self-avoidance in the mammalian nervous system. Nature. 2012 Aug 23;488(7412):517-21. doi: 10.1038/nature11305. PubMed PMID: 22842903; PubMed Central PMCID: PMC3427422. 

View full lists of Julie Lefebvre's publications on PubMed and Google Scholar

  • Canada First Research Excellence Fund, Medicine by Design, 2019-2021 (Co-PI): Endogenous Repair with Exogenous Delivery
  • CIHR Project Grant, 2016 – 2021 (PI): Regulation of cerebellar interneuron development and circuit assembly by Protocadherins
  • NSERC Discovery Grant, 2016-2022 (PI): Molecular mechanisms to organize neurons into circuits. 
  • Scottish Rite Charitable Foundation of Canada, 2016-2019 (PI): The roles of the autism-associated clustered Protocadherins genes in inhibitory circuitry development and dysfunction.
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