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Researchers studied ultrasonic vocalizations in rat pups with a mutation in the Fmr1 gene, which causes Fragile X syndrome, the most common inherited form of autism spectrum disorder. They found that mutant pups produced fewer calls during a critical developmental window and showed delayed development of syntactic complexity in their vocal sequences compared to normal littermates. While the basic acoustic structure of individual calls remained intact, the progression toward more complex call patterns was significantly disrupted in the mutant animals.
Why it matters
This research identifies early vocal communication deficits in a genetic model of autism, suggesting that disrupted syntax development could serve as an early biomarker for atypical neurodevelopment. The findings may inform early detection strategies and intervention timing for Fragile X syndrome and related autism spectrum disorders in humans.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Communication deficits are a defining feature of autism spectrum disorder (ASD) and among the earliest detectable markers of atypical neurodevelopment. Yet how specific genetic ASD risk factors shape the developmental trajectory of vocal communication remains poorly understood. Fragile X syndrome (FXS) is the most common inherited cause of ASD, resulting from the transcriptional silencing of the FMR1 gene, and a majority of FXS individuals exhibit impaired language development and atypical vocal communication. Rodent ultrasonic vocalizations (USVs) produced during maternal isolation provide a tractable model for studying the developmental trajectory of early vocal communication in FXS. Here, we characterized isolation-induced USVs in Fmr1 knockout (KO) and littermate wildtype (WT) rats from postnatal days 3-21 to determine whether Fmr1 mutation disrupts the acoustic structure, temporal organization, or sequential syntax of USVs across postnatal development. We found that Fmr1 KO rat pups exhibited reduced call number during the peak developmental window for isolation-induced calling (p6-p10), while acoustic structure and temporal organization were largely preserved. Network analysis of call transitions revealed that WT pups exhibited a progressive increase in syntactic complexity from p3-p10. However, this developmental trajectory was significantly altered and delayed in Fmr1 KO pups. Together, these findings demonstrate that Fmr1 mutation not only disrupts vocal production but the developmental expansion of syntactic flexibility in rats, highlighting USV syntax as a sensitive marker of atypical communicative development in FXS models.
Source: Disrupted Developmental Trajectory of Ultrasonic Vocalizations in a Rat Model of Fragile X Syndrome