The dominant mental timelines of native Chinese speakers (Exp1) and Mandarin learners of near-native proficiency (Exp2) was examined with the spontaneous gesture task. The results demonstrated that (1) both groups produced horizontal, vertical, sagittal, fused horizontal and vertical, and fused horizontal and sagittal gestures for all kinds of Chinese temporal words, indicating a strong preference for horizontal over vertical gestures. (2) Negligible correlations between immediate spatio-temporal metaphors and the mental timelines were observed, with an almost non-existent difference in gesture distribution across metaphorical types between the two groups. The findings indicate that (1) the horizontal mental timeline is the dominant timeline for two groups; (2) visuospatial experience exerts a greater influence on temporal cognition; (3) mental timelines formed by the long-term effects of language may operate beyond the immediate metaphors, similar to the horizontal gestures. A unified model proposing embodied experience as the mechanism for activating mental timelines is presented.

Dynamic change of mitochondrial morphology and distribution along neuronal branches are essential for neural circuitry formation and synaptic efficacy. However, the underlying mechanism remains elusive. We show here that Pink1 knockout (KO) mice display defective dendritic spine maturation, reduced axonal synaptic vesicles, abnormal synaptic connection, and attenuated long-term synaptic potentiation (LTP). Drp1 activation via S616 phosphorylation rescues deficits of spine maturation in Pink1 KO neurons. Notably, mice harboring a knockin (KI) phosphor-null Drp1^S616A recapitulate spine immaturity and synaptic abnormality identified in Pink1 KO mice. Chemical LTP (cLTP) induces Drp1^S616 phosphorylation in a PINK1-dependent manner. Moreover, phosphor-mimetic Drp1^S616D restores reduced dendritic spine localization of mitochondria in Pink1 KO neurons. Together, this study provides the first in vivo evidence of functional regulation of Drp1 by phosphorylation and suggests that PINK1-Drp1^S616 phosphorylation coupling is essential for convergence between mitochondrial dynamics and neural circuitry formation and refinement.