Delayed degeneration of the optic tract and neurons in the superior colliculus after forebrain ischemia.

Neuronal damage induced by 15-min forebrain ischemia was investigated in adult rats 1-5 days (short-term group) and 1-5 months (long-term group) after the initial ischemic attack. In addition to the vulnerable areas reported previously, we observed that the optic tract was also very susceptible. Degeneration of the optic tract and subsequent transsynaptic cell death in the superior colliculus developed slowly and was observed only in the long-term group. The delayed, progressive neuronal damage in this sensory system may serve as a suitable model to investigate the mechanisms of long-term changes in the injured brain.