How stable are dendritic spines in the adult cortex, and does learning make new ones? · Grey Matter

Imaging the same dendrites over weeks in the mouse neocortex shows that in six-month-old mice about three quarters of spines persist for at least eight days, and spines that survive that long almost all last the rest of the observation; a minority are transient, appearing and vanishing within a few days.

How stable are dendritic spines in the adult cortex, and does learning make new ones?

Imaging the same dendrites over weeks in the mouse neocortex shows that in six-month-old mice about three quarters of spines persist for at least eight days, and spines that survive that long almost all last the rest of the observation; a minority are transient, appearing and vanishing within a few days. Turnover is much higher in young animals and falls with age. Learning a new motor or sensory task adds new spines on particular dendrites, some of which stabilise along with the skill, while potentiated spines enlarge. The adult cortex is therefore mostly stable, with a small turnover that learning can bias.