Neocortical neurogenesis in humans is restricted to development.
Level 4 - case-series / case-control
Level 4 by design analogy (postmortem human tissue observational study using retrospective 14C birth dating and BrdU labeling).
PubMed 16901981 · doi:10.1073/pnas.0605177103
What was done
Assessed the age of neurons and cell turnover across major areas of the human cerebral neocortex using postmortem tissue analysis. The authors measured the integration of bomb-pulse 14C into genomic DNA to retroactively date neurons and analyzed neocortical tissue from patients previously administered BrdU to identify dividing cells.
What was found
The abstract reports no numerical values, rates, or confidence intervals. Qualitatively, nonneuronal cells in the human cerebral neocortex demonstrated turnover, whereas neocortical neurons were found to be generated perinatally without detectable adult generation.
Why it matters
It clarifies a major neurobiology debate by showing that, unlike certain other mammalian regions or nonneuronal brain cells, human neocortical neurons are formed during development and are not continually replenished in adulthood.
Limits
The abstract does not disclose the sample size, subject demographics, postmortem intervals, or underlying medical histories of the patients. The conclusion of no adult neurogenesis is bounded by the detection sensitivity of the 14C and BrdU assays.
Cited by
- context Adults have approximately 100 billion neurons in their brain and they are the exact same neurons present at birth because neurons are never replaced.