Final answer:
The death of new neurons occurs if they are not involved in learning or other stimulating activities, with learning and exercises increasing their survival.
Step-by-step explanation:
The process of neurogenesis, or the birth of new neurons, continues into adulthood, with about 1000 new neurons developing daily in the hippocampus, a brain structure involved in learning and memory. However, most of these new neurons will die if not involved in learning processes or stimulated through exercise, as they are crucial both for learning and memory formation. The exact timespan for the survival of new neurons without learning is not specified, but researchers imply that the survival rate increases with learning tasks. It's also suggested that antidepressants and exercise can promote the growth and survival of these new neurons.
The issue of neurons dying if effective learning doesn't occur is mainly due to the limited nature of neurogenesis in adult humans. Research indicates that new neurons' survival is correlated with how well learning occurs. Thus, although there is not a specific timeframe given before new neurons die, the implication is that without engagement in learning or other stimulating activities, such as exercise, these neurons will not survive long.