Old brains can make new neurons, study finds

But new neurons in older brains may make fewer connections.

A neural stem cell in the brain. Image: Maura Boldrini / Columbia University Vagelos College of Physicians and Surgeons.
A neural stem cell in the brain. Image: Maura Boldrini / Columbia University Vagelos College of Physicians and Surgeons.

A new research by the Columbia University Vagelos College of Physicians and Surgeons suggests that human brain makes new neurons throughout life. Scientists were able to pursue this research by setting up a brain bank and collecting postmortem and extensive clinical information on the donors.

Lead author Maura Boldrini, MD, PhD, a research scientist in psychiatry and a member of the Columbia Stem Cell Initiative said, “Previous studies of animal brains have led many neuroscientists to conclude that the capacity for neurogenesis, or the production of new neurons, declines with age and virtually ceases in the mature brain. In mice, researchers have shown that neurogenesis drops pretty dramatically after middle age.”

The mind’s hippocampus, which is in charge of memory and learning, has been a noteworthy focal point of concentrates on neurogenesis and undifferentiated cell science. Despite the fact that neuroimaging investigations of people demonstrate that proceeded with development in this structure happens in adulthood, numerous researchers have contended this speaks to existing neurons becoming bigger, or an extension of veins or other interior help structures, instead of the expansion of new neurons.

To address the question, investigators dissected and examined a representative sample of human hippocampi from healthy people of different ages after they died. After Mann and his partners gathered an expired benefactor’s cerebrum, they acquired the greater part of the contributor’s pertinent restorative records and directed a “mental post-mortem examination.”

Using interviews with loved ones, the specialists decided if the subject may have had a neurological or mental issue at the season of death. The subsequent accumulation of brains has turned into a remarkable asset for neuroscience, enabling specialists to perform nitty gritty investigations on human brains speaking to the entire range of life, wellbeing, and ailment.

Scientists also used a combination of molecular probes and mathematical modeling to track neurogenesis in brains from 28 healthy donors ranging in age from 14 to 79 years old. Based on the prevailing view in the field, they expected to see neurogenesis decline with age. It didn’t.

J. John Mann, MD, the Paul Janssen Professor of Translational Neuroscience in Columbia’s Department of Psychiatry said, “It does appear to be the case that neurogenesis in the hippocampus is remarkably preserved in human beings.”

A neural stem cell in the brain. Image: Maura Boldrini / Columbia University Vagelos College of Physicians and Surgeons.
A neural stem cell in the brain. Image: Maura Boldrini / Columbia University Vagelos College of Physicians and Surgeons.

Though the brain bank was essential to the study, the researchers also had to develop rigorous methods to quantify the neurogenic potential of each hippocampus. Counting and analyzing all of the cells is impractical; the human hippocampus is much too large. Instead, Boldrini used mathematical models to extrapolate from smaller sections, yielding an estimate of the numbers of different types of cells and the distribution of specific protein markers in the whole hippocampus.

The analysis revealed that the older brains had less vascular development, and the neurons in older hippocampi expressed lower levels of proteins associated with plasticity, or the formation of new neural connections.

The results point to a new model of brain aging, in which older brains retain the ability to make new neurons but may become less able to form new connections between them and keep them supplied with oxygen.

Boldrini said, “We found there were on the order of thousands of neuroprogenitor cells and immature neurons both in the youngest and the oldest people analyzed.”

“It is possible that the changes we see in the older brains are related to some cognitive-emotional changes that occur with aging and exercise, diet, and medications may help, but future studies are needed to investigate these ideas.”

Now the researchers hope to explore the underlying mechanisms for the changes they found in older brains using stem-cell culture techniques in collaboration with the Columbia University Stem Cell Initiative.

The research published today in the journal Cell Stem Cell.

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