1: Enhancing Memory processing
Psychopharmacology (Berl). 2014 Oct;231(19):3879-88. doi: 10.1007/s00213-014-3526-1. Epub 2014 Mar 19.
Green tea extract enhances parieto-frontal connectivity during working memory processing.
Rationale: It has been proposed that green tea extract may have a beneficial impact on cognitive functioning, suggesting promising clinical implications. However, the neural mechanisms underlying this putative cognitive enhancing effect of green tea extract still remain unknown.
Objectives: This study investigates whether the intake of green tea extract modulates effective brain connectivity during working memory processing and whether connectivity parameters are related to task performance.
Material and methods: Using a double-blind, counterbalanced, within-subject design, 12 healthy volunteers received a milk whey-based soft drink containing 27.5 g of green tea extract or a milk whey-based soft drink without green tea as control substance while undergoing functional magnetic resonance imaging. Working memory effect on effective connectivity between frontal and parietal brain regions was evaluated using dynamic causal modeling.
Results: Green tea extract increased the working memory induced modulation of connectivity from the right superior parietal lobule to the middle frontal gyrus. Notably, the magnitude of green tea induced increase in parieto-frontal connectivity positively correlated with improvement in task performance.
Conclusions: Our findings provide first evidence for the putative beneficial effect of green tea on cognitive functioning, in particular, on working memory processing at the neural system level by suggesting changes in short-term plasticity of parieto-frontal brain connections. Modeling effective connectivity among frontal and parietal brain regions during working memory processing might help to assess the efficacy of green tea for the treatment of cognitive impairments in psychiatric disorders such as dementia.
2: Learning and Memory:
Article first published online: 13 JUN 2012 DOI: 10.1002/mnfr.20120003
Green tea epigallocatechin-3-gallate (EGCG) promotes neural progenitor cell proliferation and sonic hedgehog pathway activation during adult hippocampal neurogenesis
Yanyan Wang1,†, Maoquan Li2,3,†, Xueqing Xu1, Min Song1, Huansheng Tao1 andYun Bai1,*
Scope: Adult hippocampal neurogenesis is a lifelong feature of brain plasticity that appears to be critically involved in adult brain function and neurological disease. Recent studies suggest that (–)-epigallocatechin-3-gallate (EGCG), which is the main polyphenolic constituent of green tea, may be used for the prevention and treatment of various neurodegenerative diseases. We hypothesized that EGCG promotes adult neurogenesis, which may be beneficial to hippocampus-dependent learning and memory.
Methods and Results: We show that EGCG treatment significantly increased the number of 5-bromo-2′-deoxyuridine (BrdU)-labeled cells in adult hippocampal neural progenitor cell (NPC) cultures and in the dentate gyrus of adult mice. Meanwhile, EGCG markedly improved spatial cognition in mice. These events are associated with the sonic hedgehog (Shh) signaling pathway. We observed that EGCG triggered a robust upregulation of Shh receptor (Patched) mRNA and protein expression in cultured NPCs as well as an upregulation of the downstream Shh transcriptional target Gli1. These changes were further confirmed in the hippocampus of mice administered EGCG. The blockage of the Shh signal with the pharmacological inhibitor cyclopamine attenuated EGCG-induced hippocampal neurogenesis.
Conclusions: Our results provide strong evidence that EGCG enhances adult hippocampal neurogenesis.