抄録
Visual inputs to the superior colliculus were investigated by recording field potentials in different layers of the superior colliculus following electrical stimulation of the optic chiasma and photo-stimulation with flash light in anesthetized (isoflurane 1.5 - 2.0%) and immobilized macaque monkeys (n = 3). Electrical and photo-stimulation induced a slow negative field potential in the superficial layers (depth 0 - 1000 μm from the dorsal surface) which was reversed in the intermediate and deep layers (depth 1000 - 2000 μm) at the latency of 6 - 8 ms and 38 - 46 ms, respectively. Sharp negative field potentials composed of multiple spike activities overrode the slow negative field potential at the depth of 400 - 800 μm. When bicuculline (10 mM, 2 μl) was injected into the intermediate and deep layers, a negative field potential was induced in these layers with a latency of approximately 13 ms (electrical stimulation) and about 45 ms (photo-stimulation), which lasted for 100 - 150 ms. When bicuculline was injected into the superficial layer, the negative field potential in the superficial layer was enhanced but the field responses in the intermediate and deep layers were unchanged. These results have suggested that visual inputs induce strong activation of intermediate and deep layer neurons in the superior colliculus when these layers are released from GABAA receptor mediated inhibition. [Jpn J Physiol 54 Suppl:S181 (2004)]
