Glossary
Neurogenesis
What is Neurogenesis?
Neurogenesis is the generation of new neurons from precursor cells. It occurs during development, and adult neurogenesis is extensively studied in animals. Evidence for adult human hippocampal neurogenesis has grown, while its extent and functional roles remain under investigation.
How it works
Animal work shows that hippocampal neurogenesis can respond to environmental conditions. Human studies use tissue markers and molecular methods that require careful interpretation. Disouky and colleagues (2026) identified neural stem cells, neuroblasts and immature neurons in post-mortem hippocampal samples, with differences across aging and cognitive-status groups.
From precursor cell to functioning neuron
Adult hippocampal research focuses particularly on the dentate gyrus, a part of the hippocampus. In animal studies, precursor cells divide, some of their descendants differentiate toward a neuronal identity, and surviving new neurons mature and become incorporated into existing circuits. Proliferation, survival and functional maturation are therefore different steps: more dividing cells does not necessarily mean an equivalent increase in functioning neurons.
In adult mice, van Praag and colleagues (2002) labeled dividing cells and later recorded properties of the resulting neurons, including action potentials and synaptic inputs. This connects the cell-birth question with the question of whether new cells participate in neural signaling.
Environmental influences in animal studies
A mouse experiment by Fabel and colleagues (2009) distinguished wheel running, which increased precursor proliferation, from environmental enrichment, which supported the survival of newborn cells. Combining the two produced an additional increase in new neurons. These findings illustrate how an environment can affect different stages of neurogenesis in animals; they do not establish that a particular exercise routine grows new neurons in a living human brain.
Applied example
A randomized exercise study in older adults found increased hippocampal volume and better spatial memory. That finding is consistent with brain plasticity, but it did not directly measure new neurons in living human participants.
Why it matters
Neurogenesis is one area of research on brain plasticity. It should not be assumed to explain every cognitive benefit of exercise, learning or antidepressant treatment.
Evidence note: Disouky and colleagues (2026) study human tissue; Erickson and colleagues (2011) measure exercise-related MRI volume and memory changes. These are different measurements.