Figure 8.

A schematic presentation of a unified-hybrid model of spinogenesis/synaptogenesis in motoneurons compared to pyramidal/Purkinje neurons at different developmental stages involving previously described models. (a) In motoneurons, the Vaughn/filopodial model (left) predominates during embryonic, prenatal, and neonatal development but becomes less common during juvenile development, where the Sotelo model (middle) becomes more frequent. The Miller/Peters model (right) may play a role in adult plasticity. (b) The sequence of spinogenesis/synaptogenesis in motoneurons seems to significantly differ from that described for pyramidal and Purkinje cells. The Sotelo model predominates in spinogenesis in pyramidal/Purkinje cells during embryonic/prenatal period. The filopodial model is less involved in all cell types in the adult but is likely reactivated as part of the regenerative/remodelling processes following injury/neuropathological conditions (red lines). 1, 2, and 3 indicate the sequence of pre- and postsynaptic development; filled circles represent postsynaptic receptor clusters.