[Effects of optic nerve section in baboons on the geniculate and cortical spike activity during various states of vigilance].

Eye movement potentials during wakefulness (EMPs) and so-called spike (PGO) activities were studied in 4 adult baboons before and after optic nerve (ON) section. The latter was performed either in two stages at a 23-day interval or simultaneously. During wakefulness in the intact animal, triphasic EMPs were observed in darkness with smaller amplitude and longer duration than in the light. After section of one ON, the 3 EMP components persisted, but with a smaller amplitude of the first wave. After section of the second ON morphological changes appeared: the amplitude and duration of the potentials were intermediate between those noted in darkness and light but with an intermingled sharp spike. Geniculate EMPs reappeared 11 days after simultaneous ON section, with the same evolution as previously described. During slow wave and REM sleep, intact animals presented lateral geniculate (LG) monophasic and biphasic spikes, called spikes I and II. At the cortex, they occurred either generalized or limited to one area (anterior or posterior) and were called pontogeniculocortical spikes (PGC). After section of one ON, the pattern of occurrence of phasic activities remained identical in LG. Sharp spikes (spike III) appeared; then their occurrence increased. At the end of the second month after the second section, only spikes II and III remained, spike I disappearing, while PGC amplitude diminished. When both ONs were cut simultaneously, spike III was observed from the first day and PGC activity tended to disappear partially for 11 days. Their later evolution was similar to that noted previously. However, changes were seen earlier (the highest rate of spike III occurring at day 35). In both cases, PGC spikes at the cortex increased in amplitude and frequency of occurrence.