摘要
THE nucleus isthmi (NI) in lower vertebrates and its mammalian analogue, the nucleus para-bigeminalis, are all visual centres. They receive their tectal input ipsilaterally and project backipsilaterally in teleosts and birds, or bilaterally in amphibians and reptiles, as well as in mam-mals. It is well known that NI receives its visual excitation through the ipsilateral optic tec-tum (OT). NI mainly exerts inhibition on the ipsilateral OT in frogs.A recent study
