A new study points toward new neuron formation in the hippocampus of the adult brain, with important implications for memory and disease.
Scientists have debated whether new neuron growth, or neurogenesis, was possible in the adult hippocampus, the region of the brain responsible for learning and memory. Research has long suggested they could, a 1998 paper found the first evidence for neurogenesis, but other studies contradicted those findings.
In the new study, researchers from Spain tested different methods of preserving brain tissue. They found results leading conclusions about whether or not neurogenesis is possible were dependent on how quickly the brain tissue was preserved and what chemicals were used. So conclusions were being skewed based on these experimental flaws. Brain tissue has to be preserved within a few hours after death, and specific chemicals used to preserve the tissue, or proteins identifying newly developing cells are destroyed.
Past research has missed the presence of these cells, because the brain tissue was not properly preserved. Previous brain studies have been tainted by this methodological error and the new study raises the bar for future studies.
In the study, researchers also examined the brains of people who died at various stages of Alzheimer’s disease and the brains of people who died with healthy brains using this more precise methodology. The brains of people with Alzheimer’s had few if any signs of new neurons in the hippocampus and in the brains where the disease was farther progressed there were even fewer signs of newly developing neurons. The findings suggest that the loss of new neurons could be used as an early indicator for the onset of Alzheimer’s.
In rat and mice studies, researchers have shown that growth of new neurons can be stimulated with increased exercise or with more stimulating environments.