Impaired Functional Connectivity Underlies Fragile X Syndrome

Lital Gildin, Rossana Rauti, Ofir Vardi, Liron Kuznitsov-Yanovsky, Ben M. Maoz, Menahem Segal*, Dalit Ben-Yosef

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Fragile X syndrome (FXS), the most common form of inherited intellectual disability, is caused by a developmentally regulated silencing of the FMR1 gene, but its effect on human neuronal network development and function is not fully understood. Here, we isolated isogenic human embryonic stem cell (hESC) subclones—one with a full FX mutation and one that is free of the mutation (control) but shares the same genetic background—differentiated them into induced neurons (iNs) by forced expression of NEUROG-1, and compared the functional properties of the derived neuronal networks. High-throughput image analysis demonstrates that FX-iNs have significantly smaller cell bodies and reduced arborizations than the control. Both FX-and control-neurons can discharge repetitive action potentials, and FX neuronal networks are also able to generate spontaneous excitatory synaptic currents with slight differences from the control, demonstrating that iNs generate more mature neuronal networks than the previously used protocols. MEA analysis demonstrated that FX networks are hyperexcitable with significantly higher spontaneous burst-firing activity compared to the control. Most importantly, cross-correlation analysis enabled quantification of network connectivity to demonstrate that the FX neuronal networks are significantly less synchronous than the control, which can explain the origin of the development of intellectual dysfunction associated with FXS.

Original languageEnglish
Article number2048
JournalInternational Journal of Molecular Sciences
Issue number4
StatePublished - 1 Feb 2022


FundersFunder number
Aufzien Family Center for the Prevention and Treatment of Parkinson’s Disease
Biomorasha, Israel Science Foundation1471/17
Clore Center for Biological Physics
Harvard University
Tel Aviv University
Azrieli Foundation
Ministry of Science and Technology, Israel3-17351
Sagol School of Neuroscience, Tel Aviv University


    • Disease modeling
    • Electrophysiology
    • Fragile X syndrome
    • Human embryonic stem cells
    • MEA
    • Neural differentiation


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