Nature Publishes Latest Findings on Neurogenesis in Hippocampus by Fudan Professor


Recently, the research team led by Yang Zhengang, Professor of the Institutes of Brain Science Fudan University (IOBS) and Department of Neurology in Zhongshan Hospital, made a breakthrough in an international cooperative project. Their result provided new evidence for the hypothesis that no newborn neurons exist in hippocampus of adults’ brain. The paper entitled “Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults” was published in Nature, one of the world’s top academic journals.
Apart from Fudan University, also in the project were research teams from the University of California, San Francisco (UCSF), the University of Valencia, the University of California, Los Angeles (UCLA), etc. Doctor Qi Dashi from IOBS of Fudan Univesity was one of the co-second authors, and Professor Yang Zhengang from Fudan University is one of  co-corresponding authors. Fudan University is the only Chinese university participating in this project.

The Youngest Neuron in Human Brain is Born in Childhood
There are approximately 1618 newborn neurons per square millimeter in an infant’s brain. As human ages, this number decreases sharply. By 1-year-old, it decreases by 5 times, 7-year-old 23 times, and 13-year-old almost 700 times - only 2.4 newborn neurons per square millimeter exist in hippocampus. Then no more neurons are born. One leading cause of this phenomenon the absence of an enabling niche for neural stem cells in hippocampus.
After 4 years’ efforts and based on the analysis of 59 cases of human hippocampus in different ages, Professor Arturo Alvarez-Buylla (UCSF) discovered that the youngest neuron in human brain was born in childhood. Such conclusion provided new evidence for the debate of adults’ ability to produce neurons.
To better prove the findings, Professor Yang Zhengang conduct his research on rhesus monkeys. Thanks to the abundance of animal resources in China, his team focused on the analysis of nerve conditions in 10 non-primate rhesus monkeys’ brains. It is reported that human raised rhesus monkey can live 25 up to 30 years. Similar to the team’s findings concerning human brains, the number of newborn neurons in the rhesus monkeys’ brains decreases sharply as they age. Rhesus monkeys hardly produce newborn neurons when they turn 7-year-old.

Rethinking the Relation of Neurons and Learning and Memorizing Ability in Hippocampus
Neurons in hippocampus of adult birds (e.g., canaries) and rodents (e.g., rats) can be produced continuously, which is termed neurogenesis.
Does neurogenesis exist in human brain? The critical question concerning the possibility of reshaping human brains has drawn attention of many neuroscientists in the past 50 years, and the majority believes in neurogenesis.
Since researchers tend to relate newborn neurons in animal hippocampus to major issues such as learning, memory and neurogenesis, the results could be applied in the recovery and reconstruction of brain function, and to treat and cure related diseases. As far as Yang’s research is concerned, it clearly points out that, statements would require more cautious examination, such as newborn neurons are a part of the learning and memorizing ability of adults, the adjustment of adult emotions, or neurogenesis in the recovery from brain injury.