Intracellular recording and morphology of tectal neurons activated by contralateral nucleus isthmi in toads

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 back ipsilaterally in teleosts and birds, or bilaterally in amphibians and reptiles, as well as in mammals. It is well known that NI receives its visual excitation through the ipsilateral optic tectum (OT). NI mainly exerts inhibition on the ipsilateral OT in frogs . A recent study by Wang et al. has indicated that the parvocellular (Ipc) and magnocellular (Imc) components of the pigeon NI could negatively and positively modulate ipsilaterally tectal responses, respectively. These findings have been confirmed by our microiontophoretic studies.