Some scientists still deny adult brains produce new neurons

Evidence

What are we to understand by ”neuronal renewal” or ”secondary neurogenesis”? According to what we have just said, it would seem that a primary plasticity—morphogenic —is followed by a modulational plasticity that modifies synaptic efficacy but does not affect the anatomical stability of the brain, as though this plasticity somehow operated inside a closed system. ”Certain scientists,” declares Heather Cameron, ”still cling to a very rigorous form of the hypothesis of a stable brain, according to which there is no anatomical plasticity in the adult brain, and especially not in the cortex; they hold that the functional plasticity underlying learning mechanisms requires only modifications in the force of the synapses, produced by a modification in the receptors or in the intercellular environment of the neuron at the molecular level.” But this dogma of the stable brain is not quite right. — Catherine Malabou, What Should We Do with Our Brain?, 95

Categorization

• DEFINE: Defines the morphogenic vs. modulational distinction in plasticity — the functional vs. anatomical layer that the reader needs to separate plasticity from flexibility precisely.