Download Neurogenesis

Adult Neurogenesis
CHALLENGING THE DOGMA
Neurogenesis
oThe process by which new neurons are generated in the brain
oUntil the 1990’s, it was widely accepted that neurogenesis did not occur in the adult brain
o “In the adult centers the nerve paths are something fixed, ended and immutable. Everything may die,
nothing may be regenerated.”
Support for Adult Neurogenesis
o3H- Thymidine Autoradiography
o Technique used to identify proliferating cells
o1960’s: Altman published a series of papers reporting thymidine autoradiographic evidence for
new neurons
o In the hippocampus , the olfactory bulb, and in the cerebral cortex of an adult rat
o Neocortex of an adult cat
o1970’s: Kaplan finds further evidence for the notion of neurogenesis
o Cerebral cortex of adult rats
o Mitosis in the brain of adult rhesus macaque monkeys
Opposition to Adult Neurogenesis
oPasko Rakic
o Leading student of primate brain development
o “All neurons of the rhesus monkey brain are generated during prenatal and postnatal life”
oEckenhoff and Rakic
o Failed to find support for neurogenesis in the adult
o Questioned the reports of adult neurogenesis in rats with the suggestion that they never stop growing
Altman’s Work is Vindicated
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Avian Neurogenesis
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New Techniques for Detecting Neurogenesis
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Demonstration of neurogenesis in adult birds
New methods for labeling new cells
Regulation of Neurogenesis
Current Research
oAkers et. al. (2014)
o Because not all experiences are ultimately remembered, it is likely that forgetting processes
continuously clear stored hippocampal information
o High levels of neurogenesis disrupt established hippocampus- dependent memories
o Because neurogenesis reconfigures hippocampal circuits (thus reducing the ability of a given set of cues to reinvoke the same
pattern of activity)