Nerve cell production in the human brain is directly related to learning and memory, according to a new study from the University of Florida. The findings, published online and in an upcoming print issue of the journal Brain, are the first to show such a link in humans.
Scientists have long observed that new nerve cells generate in the hippocampus, a memory-related area of the brain. Animal studies have shown that an increase in nerve cell production in this area improves memory, while a disruption of new nerve cell generation results in memory loss.
To investigate if these findings applied to humans, UF researchers, in association with colleagues in Germany, studied 23 epileptic patients with differing degrees of associated memory loss. They recorded and evaluated the patients’ memory functions and also studied their hippocampus stem cells removed during epilepsy surgery. Researchers were able to observe if and how these stem cells multiplied and changed into other types of nerve cells.
In patients with normal memory scores, stem cells were able to proliferate in laboratory cultures. However, the stem cells of patients with low memory scores could not generate new cells. These findings demonstrate a strong correlation between the patient’s memory and the ability to generate new cells.
“The study gives us insights on how to approach the problem of cognitive aging and age-related memory loss, with the hope of developing therapies that can improve cognitive health in the aging,” said Dr. J. Lee Dockery, a trustee of the McKnight Brain Research Foundation.
Florian Siebzehnrubl, co-first author of the study and a postdoctoral researcher in neuroscience at the UF College of Medicine, says, “The findings suggest that if we can increase the regeneration of nerve cells in the hippocampus we can alleviate or prevent memory loss in humans. This process gives us what pharmacologists call a ‘druggable target.’”
The results could reach beyond epilepsy, but researchers believe more studies with larger numbers of patients as well as more tests on other brain-related structures and functions would be needed first. Also, researchers need to understand exactly how the new nerve cells affect learning and memory.
“It is interesting and provocative, but we need to do more work because it’s not clear what comes first — the severe epilepsy or the change in the stem cells,” said Dr. Jack Parent, an associate professor of neurology and co-director of the EEG/Epilepsy Program at the University of Michigan, who was not involved in the study. “It was really interesting to correlate stem cell activity in tissue culture with the response of the patients.”
Scientists are still trying to understand exactly what stimulates nerve cell production in the brain and have been studying certain compounds they believe could play a role. Animal studies have given clues into possible triggers, but it is still undetermined which are important and which are minor, the researchers said.
In further studies, efforts to determine relevant pathways and how to switch them on will be a crucial component. Noninvasive imaging procedures such as fMRI and PET could help reveal this process over time.
“Probably everyone will experience some degree of age-related memory loss as a result of the normal aging process,” said Dennis A. Steindler, one of the study’s senior authors and executive director of UF’s McKnight Brain Institute.
“There is no reason to believe that this is irreversible, and we must find new approaches and therapeutics for allowing everyone to experience productivity and lifelong memory and learning. Facilitating the generation of new functional neurons in our brains throughout life may be one such approach for helping this cause.”
Source: University of Florida