Effects of oral motor intervention on the development of brain functional network asymmetry in preterm infants: a randomized controlled trial based on resting-state fNIRS

The aim of this study was to investigate whether the Preterm Infant Oral Motor Intervention (PIOMI) promotes the development of hemispheric functional network asymmetry in preterm infants and to explore its central neural mechanisms. This study was a prospective, assessor‑blind, randomized controlled trial. A total of 66 preterm infants (33 per group) completed the study. Preterm infants with gestational age 28–34 weeks were randomly assigned to either a PIOMI group (oral motor intervention twice daily for 14 days) or a control group (routine care). Resting‑state functional near‑infrared spectroscopy (fNIRS) data were acquired after the intervention. Hemispheric functional networks were constructed using graph theory analysis. Primary outcomes included global efficiency and local efficiency of the left and right hemispheres. The asymmetry index (AI), derived from these metrics, was evaluated as a secondary outcome to quantify hemispheric lateralization. In the PIOMI group, the left hemisphere showed significantly higher global efficiency and local efficiency compared with the control group ( P < 0.025). The asymmetry index of the left frontal and temporal lobes was positive and significantly higher in the PIOMI group ( P < 0.05), indicating left‑hemisphere dominance. No significant intergroup differences were observed in the right hemisphere. Both groups exhibited small-world network topology (normalized global efficiency ≈ 1, normalized local efficiency > 1), and the PIOMI group demonstrated enhanced left-hemispheric local efficiency without altering global topological architecture. Individual‑level analysis confirmed consistent left‑hemisphere lateralization in the PIOMI group. A 14‑day oral motor intervention specifically enhances global and local functional network efficiency in the left hemisphere of preterm infants and induces left‑hemisphere lateralization. These findings provide preliminary neuroplasticity-based evidence for the short-term effects of PIOMI on hemispheric functional network organization in preterm infants in the neonatal intensive care unit. Trial registration ChiCTR2600126146, registered on 04 June 2026, retrospectively registered.