Parkinson’s disease (PD) is a common and debilitating degenerative disease resulting from massive degenerative loss of dopamine neurons, particularly in the substantia nigra. The most classic therapy for PD is levodopa administration, but the efficacy of levodopa treatment declines as the disease progresses. The neuroprotective strategies to rescue nigral dopamine neurons from progressive death are currently being explored, and among them, the Chinese herbs and herbal extracts have shown potential clinical benefit in attenuating the progression of PD in human beings. Growing studies have indicated that a range of Chinese herbs or herbal extracts such as green tea polyphenols or catechins, panax ginseng and ginsenoside, ginkgo biloba and EGb 761, polygonum, triptolide from tripterygium wilfordii hook, polysaccharides from the flowers of nerium indicum, oil from ganoderma lucidum spores, huperzine and stepholidine are able to attenuate degeneration of dopamine neurons and sympotoms caused by the neurotoxins 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) and 6-hydroxydopamine (6-OHDA) in vitro and in vivo conditions. In addition, accumulating data have suggested that Chinese herbs or herbal extracts may promote neuronal survival and neurite growth, and facilitate functional recovery of brain injures by invoking distinct mechanisms that are related to their neuroprotective roles as the antioxidants, dopamine transporter inhibitor, monoamine oxidase inhibitor, free radical scavengers, chelators of harmful metal ions, modulating cell survival genes and signaling, anti-apoptosis activity, and even improving brain blood circulation. New pharmaceutical strategies against PD will hopefully be discovered by understanding the various active entities and valuable combinations that contribute to the biological effects of Chinese herbs and herbal extracts.

Significance: The hippocampus with its dense reciprocal axonal projections to and from cortex is widely believed to mediate numerous cognitive functions. However, it is unknown whether and how specific hippocampal–cortical activity contributes to the brain-wide functional connectivity. Here, we use optogenetics and fMRI to examine how excitatory neural activity initiated in the dorsal dentate gyrus of the hippocampus propagates and modulates resting-state fMRI (rsfMRI) connectivity. We discover its robust propagation brain-wide at low frequency (1 Hz), which enhances interhemispheric rsfMRI connectivity and cortical and subcortical visual responses. Our findings highlight the important role of slow hippocampal–cortical oscillatory activity in driving brain-wide rsfMRI connectivity and mediating sensory processing.