So, it turns out that neurogenesis in primates is quite a bit different than in rodents. It’s been over 10 years since adult neurogenesis was first described in the adult primate hippocampus and yet much of the basic work has yet to be done. That’s where this new study by Kohler et al. come in. The data are not so new actually — they were first presented at the Society for Neuroscience meeting back in 2005.
Their question was simple: at what rate do newborn neurons mature in nonhuman primates? Their methods were also simple and easy to compare to previous studies in rodents: they used BrdU to label newborn cells and then they colabeled the BrdU+ cells with immature (DCX) and mature (NeuN) neuronal markers at different cell ages: 2 days, 2 weeks, 6 weeks, 11 weeks and 23 weeks.
First, they found that after labeling with BrdU the number of BrdU+ cells increased over the next 6 weeks. This fits well with the data from Gould and suggests that precursor cells in primates may divide much more infrequently, taking up the BrdU label at injection, retaining it for several days or weeks and then giving rise to additional BrdU+ cells upon redivision, etc etc until the BrdU is diluted. Continue reading New neurons mature very slowly in monkeys
For obvious reasons, studying neurogenesis in primates is useful. Primates are phylogenetically more related to us than rodents, and so understanding their nervous system can better help us to understand our own. For over a decade we have known that neurogenesis continues in adulthood in primates and in many ways, the process is similar to what has been observed in rodents. For example, neurogenesis is reduced with age in primates, is decreased by stress, increased in pathological conditions such as epilepsy, and increased by antidepressant treatment.
My goal in compiling this list was to assess the magnitude of adult neurogenesis in primates. It’s definitely more challenging than assessing the magnitude of neurogenesis in rodents, which we know much more about, and so I had put it off. At this point I haven’t reached a clear conclusion but, in quickly skimming these papers, the number of proliferating cells and/or new neurons averages thousand(s) of cells in the young adult primate hippocampus. The range is much much larger, and many studies cannot be easily compared due to variability in the methods, which is partly understandable since primates are scarce and are often used in multiple studies, thereby limiting the analyses that can be performed.
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