LIGHT-INDUCED EEG DESYNCHRONIZATION AND BEHAVIORAL AROUSAL IN RATS WITH RESTORED RETINOCOLLICULAR PROJECTION BY PERIPHERAL-NERVE GRAFT

Peripheral nerve (PN) was grafted to sectioned optic nerve and was bri dged to the superior colliculus in adult rats. To test functional reco very of restored retinocollicular pathway, we examined cortical electr oencephalogram (EEG) and behavioral arousal responses to light stimuli . In eight of 10 recording trials in PN grafted rats (n = 6) and in al l of eight trials in normal rats (n = 5), cortical EEGs showed desynch ronization to light stimuli. On the other hand, after bilateral sectio ns of the optic nerve (n = 3) EEG desynchronization to light disappear ed while it was induced by a white noise. Mean threshold duration of l ight for EEG desynchronization was significantly longer in the PN graf ted rats (440 ms) than in normal rats (173 ms). In three of six trials in PN grafted rats (n = 4), and in four of eight trials in normal rat s (n = 4), EEG desynchronization elicited by light stimulus was accomp anied by behavioral arousal responses, whereas no behavioral arousal c ould be induced by light in blind rats (n = 3). These results strongly suggest that visual information processed through the restored retino collicular pathway was further transmitted to the cerebral cortices an d ultimately resulted in behavioral arousal of the PN grafted rats.