Fig. 3. Most newly formed filopodia and spines do not persist. A , The percentage of new filopodia formed over the first 4 h that were eliminated, that persisted as filopodia, or that were transformed to spines over the next 8 h. Most filopodia were eliminated, a small percentage persisted, and fewer than 10% of filopodia were transformed to spines. There was no significant difference between filopodia formed with and without ketamine-xylazine (K-X). B , Percentage of new spines persisting for 8 h. Fewer than half of the new spines formed within the first 4 h persisted for the next 8 h. There was no significant difference between spines formed with and without K-X. C , Percentage of new spines persisting for 1 month. Fewer than 7% of new spines formed within 12 h or 2 days persisted over 1 month. Each filled circle represents a single animal. Data are presented as mean ± SD.