The maintenance of synaptic strength and specificity in the CNS may depend
on interactions among postsynaptic dendrites. We examined the effect of rem
oving a neuron on synaptic organization. A single identified postsynaptic n
euron in the adult cercal system of the cockroach was removed with photoabl
ation. After a 30 d recovery period, the synaptic connectivity and morpholo
gy of the intact presynaptic and postsynaptic neurons were analyzed. The sy
naptic connectivity was reorganized in a manner that was consistent with fu
nctional plasticity.
To associate anatomical changes with this reorganization, we analyzed the m
orphology of the presynaptic and postsynaptic neurons by quantitative morph
ometry. Both presynaptic and intact postsynaptic neurons maintained a stabl
e morphology after removal of a neighboring postsynaptic neuron. Using the
Hausdorff Match method (HM) (Mizrahi et al. 2000), we found that the spatia
l organization of the intact dendritic and axonal trees after ablation of a
postsynaptic neuron remained stable. Thus, interactions with neighboring n
eurons were not necessary for maintaining dendritic morphology in the adult
nervous system. However, adult central synapses were capable of adjusting
to maintain normal function.