Structural brain feature is associated with changes of masticatory performance in healthy elderly people: Evidence from longitudinal neuroimaging research over two years.

BACKGROUND: Human neuroimaging studies have revealed the association between brain structure and masticatory function. However, the majority of the studies adopted a cross-sectional design, which hardly reveals the change in masticatory function and brain structure between different timepoints, and the dynamical association between changes in masticatory function and changes in brain structure has not been elucidated. OBJECTIVE: With a longitudinal design, we assessed the association between changes in masticatory performance (MP) and regional brain volume. METHODS: Twenty-two elderly participants received assessments of the number of missing teeth and MP (via colour-changeable chewing gum) when they entered the study (i.e. the initial stage, T0 ), approximately 6 months later (T0.5 ), and approximately 1-2 years later (T1 ). Difficulty of food intake was assessed using a questionnaire. The participants received magnetic resonance imaging (MRI) at T0 and T1 . The brain volume of the motor-related area was estimated using FreeSurfer for MRI data. The associations between different stages were analysed using Spearman's rho correlation coefficients. RESULTS: (1) Individually, a smaller volume of right primary motor cortex at T0 was associated with increased MP from T0 to T1 , suggesting the brain's role in changing oral functions; (2) higher MP at T0 was associated with an increased volume of the left superior frontal cortex from T0 to T1 p, suggesting a potential effect on brain plasticity, and (3) increased difficulty to eat was associated with decrease MP but not brain volume of motor-related area. CONCLUSIONS: The preliminary findings revealed a complicated pattern of structural brain features and masticatory function in elderly people, and either the hypothesis that the brain predisposes masticatory function or the hypothesis that mastication reshapes the brain is oversimplified.

Spatiotemporal gating of Stat nuclear influx by Drosophila Npas4 in collective cell migration.

Collective migration is important to embryonic development and cancer metastasis, but migratory and nonmigratory cell fate discrimination by differential activity of signal pathways remains elusive. In Drosophila oogenesis, Jak/Stat signaling patterns the epithelial cell fates in early egg chambers but later renders motility to clustered border cells. How Jak/Stat signal spatiotemporally switches static epithelia to motile cells is largely unknown. We report that a nuclear protein, Dysfusion, resides on the inner nuclear membrane and interacts with importin α/ß and Nup153 to modulate Jak/Stat signal by attenuating Stat nuclear import. Dysfusion is ubiquitously expressed in oogenesis but specifically down-regulated in border cells when migrating. Increase of nuclear Stat by Dysfusion down-regulation triggers invasive cell behavior and maintains persistent motility. Mammalian homolog of Dysfusion (NPAS4) also negatively regulates the nuclear accumulation of STAT3 and cancer cell migration. Thus, our finding demonstrates that Dysfusion-dependent gating mechanism is conserved and may serve as a therapeutic target for Stat-mediated cancer metastasis.