[Cover]

Parkinson's disease (PD) is the second most common and fastest-growing neurodegenerative disorder. In recent years, it has been recognized that neurotransmitters other than dopamine and neuronal systems outside the basal ganglia are also associated with the pathogenesis of PD. Li et al. found that glutamatergic neurons in the caudal zona incerta (ZIc) regulate parkinsonian motor symptoms through a glutamatergic monosynaptic projection to the substantia nigra pars reticulata. Interestingly, changes in the activity of ZIcVgluT2 neurons can either induce or ameliorate parkinsonian motor impairments in healthy and PD-model mice. The cover image vividly describes this bidirectional regulation pattern: the traffic light turns red when ZIcVgluT2 neurons are hyperactive and this induces bradykinesia and impairs motor coordination. By lowering this abnormal hyperactivity, the traffic light turns green to allow amelioration of the bradykinesia and impaired motor coordination in the parkinsonian state. See pages 1–16. (Cover art by Drs Lixuan Li and Xiaoming Li).