A Brief History and Timeline

Adult mammalian neurogenesis

The research history of adult mammalian neurogenesis is a controversial one.  The first published evidence of adult neurogenesis in rodents by Joseph Altman and Gopal Das in the 1960’s was essentially ignored by the scientific community. Their findings were published in the best scientific journals, but they did not overturn the scientific “fact” that no new neurons are born into the adult brain.

In the early 70’s,  two more researchers challenged this dogma: Fernando Nottebohm and Michael Kaplan.  Dr. Nottebohm’s work showed adult neurogenesis in birds (Nottebohm, 1989), while Michael Kaplan worked on rodents. Both were criticized initially, but Kaplan’s research career was ultimately destroyed by a combination of this criticism and a lack of support from his colleagues (Kaplan, 2001).

It was eventually accepted that birds undergo adult neurogenesis; but was much harder for people to believe that adult neurogenesis occurs in mammals. The major opposition to this notion was Pasko Rakic. His papers in 1974 and 1985 effectively cast doubt upon the robust research efforts by Kaplan towards understanding adult neurogenesis. His  1985 paper entitled “Limits of Neurogenesis in Primates” was published in Science, and convinced many researchers that adult neurogenesis is restricted to evolutionarily lower order animals (rodents and birds), and that it is irrelevant for primates such as ourselves.

The field did not recover from this until the late 1990’s, when researchers including Elizabeth Gould,  Fred Gage, and Peter Eriksson published a series of papers that initiated an explosion of research on the existence, function, and implications of adult mammalian neurogenesis (Gould & Gross, 2002).  Recent research has explored a range of topics, including the molecular basis of neurogenesis, involvement in learning, environmental enrichment, neurodegenerative disorders (such as Alzheimer’s Disease and Parkinson’s Disease), and recovery from trauma and stroke. The following timeline  illustrates the progression of research in this field as a sequential list with brief descriptions of some of the key papers published in the last 50 years.

  • Key papers are color-coded by topic:
    • General existence and characterization of adult mammalian neurogenesis = Blue
    • Non-human primates = Orange
    • Humans (inlcuding neurodegenerative disorders) = Purple
    • Involvement of neurogenesis in learning and memory* = Red
    • Neurogenesis in the cortex = Green

[kml_flashembed movie="http://www.youtube.com/v/Im1qnPM3Y7w" width="640" height="385" allowfullscreen="true" fvars="fs=1" /] Interview with Tracey Shors on the involvement of adult neurogenesis in learning and memory

Abbreviations and definitions (glossary page)

Complete List of References (references page)

All images were accessed freely from flickr.com and google.com/images

Page by: Alyssa Wheeler