It has been established that the nucleus isthmi (NI) in lower vertebrates and its mammalian analogue, the nucleus parabigeminalis, receive input from the ipsilateral tectum and project back ipsilaterally in teleosts a...It has been established that the nucleus isthmi (NI) in lower vertebrates and its mammalian analogue, the nucleus parabigeminalis, receive input from the ipsilateral tectum and project back ipsilaterally in teleosts and birds, or bilaterally in amphibians, reptiles and mammals.The nucleus receives visual excitation from the ipsilateral tectum. while it mainly exerts inhibition on cells recorded from the ipsilateral tectum. A recent study by Wang and coworkers shows that the nucleus isthmi pars magnoceUularis (Imc) and展开更多
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 an...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展开更多
The previous studies showed that the two divisions of the avian nucleus isthmi, magnocellular part Imc and parvocellular part Ipc, are all visual centers, and that both parts and their cell bodies are heavily stained ...The previous studies showed that the two divisions of the avian nucleus isthmi, magnocellular part Imc and parvocellular part Ipc, are all visual centers, and that both parts and their cell bodies are heavily stained for acetylcholinesterase (ACHE).展开更多
Visual responses of 125 units have been extracellularly recorded with glass micropipettesfrom the left nucleus isthmi in the frog Rana nigromaculata, and 101 electrode tip positionsmarked with cobalt staining to recon...Visual responses of 125 units have been extracellularly recorded with glass micropipettesfrom the left nucleus isthmi in the frog Rana nigromaculata, and 101 electrode tip positionsmarked with cobalt staining to reconstruct a visual field map in the nucleus. 80% of the unitsrecorded show ON-OFF responses to a stationary spot of light and many are directionally selec-tive in response to black or white targets moving through their receptive fields. All the cobalt-marked ssots are within the nucleus, indicating that the nucleus isthmus proper is a restrictedpart of the frog visual system. There is a visual field map in the nucleus. The entire contra-lateral hemifield and the nasal 40°of the ipsilateral hemifield project on the nucleus topog-raphically. A cell-free band inside the nucleus is a boundary line separating the contralat-eral hemifield from the ipsilateral one. Dorsal to it is the contralateral field representation.The upper visual field projects on the rostral half of the nucleus and the central and medio-ventral portion of its caudal half. The lower field is represented on the dorsal and lateralpart of the caudal half. Fifteen binocular units have been found from the nucleus, 13 ofwhich arc dominantly activated by the contralateral eye, the other two are almost equallyexcited by either eye. These binocular units are mainly situated in the medulla of the rostralhalf of the nucleus isthmus.展开更多
In this study postsynaptic potentials responding to the electrical stimulation of the optic nerve and the nucleus isthmipars parvocellularis (Ipc) were intracellularly recorded from 86 tectal cells in pigeons, 13 of w...In this study postsynaptic potentials responding to the electrical stimulation of the optic nerve and the nucleus isthmipars parvocellularis (Ipc) were intracellularly recorded from 86 tectal cells in pigeons, 13 of which were marked with Lucifer yellow (LY). According to types of postsynaptic potentials and their succesion, the postsynaptic responses could be classified into four types: excitatory postsynaptic potential (EPSP)-inhibitory postsynaptic potential (IPSP) sequence (EI type), E, I and IE types.Among them, E or EI responses were mainly produced to the optic nerve stimulation, while the electrical stimulation of the lpc elicited I responses in more than half the recorded cells.LY-marked tectal cells included five ganglionic cells, four pyramidal cells, two bipolar cells and two stellate cells.The ganglionic cells were mainly located in tectal layers Ⅲ and Ⅳ, whereas the others were in layer Ⅱ.It appears from both intracellular recordings and fluorescent markings that there is some展开更多
基金Project supported by the National Natural Science Foundation of China
文摘It has been established that the nucleus isthmi (NI) in lower vertebrates and its mammalian analogue, the nucleus parabigeminalis, receive input from the ipsilateral tectum and project back ipsilaterally in teleosts and birds, or bilaterally in amphibians, reptiles and mammals.The nucleus receives visual excitation from the ipsilateral tectum. while it mainly exerts inhibition on cells recorded from the ipsilateral tectum. A recent study by Wang and coworkers shows that the nucleus isthmi pars magnoceUularis (Imc) and
文摘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
文摘The previous studies showed that the two divisions of the avian nucleus isthmi, magnocellular part Imc and parvocellular part Ipc, are all visual centers, and that both parts and their cell bodies are heavily stained for acetylcholinesterase (ACHE).
文摘Visual responses of 125 units have been extracellularly recorded with glass micropipettesfrom the left nucleus isthmi in the frog Rana nigromaculata, and 101 electrode tip positionsmarked with cobalt staining to reconstruct a visual field map in the nucleus. 80% of the unitsrecorded show ON-OFF responses to a stationary spot of light and many are directionally selec-tive in response to black or white targets moving through their receptive fields. All the cobalt-marked ssots are within the nucleus, indicating that the nucleus isthmus proper is a restrictedpart of the frog visual system. There is a visual field map in the nucleus. The entire contra-lateral hemifield and the nasal 40°of the ipsilateral hemifield project on the nucleus topog-raphically. A cell-free band inside the nucleus is a boundary line separating the contralat-eral hemifield from the ipsilateral one. Dorsal to it is the contralateral field representation.The upper visual field projects on the rostral half of the nucleus and the central and medio-ventral portion of its caudal half. The lower field is represented on the dorsal and lateralpart of the caudal half. Fifteen binocular units have been found from the nucleus, 13 ofwhich arc dominantly activated by the contralateral eye, the other two are almost equallyexcited by either eye. These binocular units are mainly situated in the medulla of the rostralhalf of the nucleus isthmus.
基金Project supported by the National Natural Science Foundation of China.
文摘In this study postsynaptic potentials responding to the electrical stimulation of the optic nerve and the nucleus isthmipars parvocellularis (Ipc) were intracellularly recorded from 86 tectal cells in pigeons, 13 of which were marked with Lucifer yellow (LY). According to types of postsynaptic potentials and their succesion, the postsynaptic responses could be classified into four types: excitatory postsynaptic potential (EPSP)-inhibitory postsynaptic potential (IPSP) sequence (EI type), E, I and IE types.Among them, E or EI responses were mainly produced to the optic nerve stimulation, while the electrical stimulation of the lpc elicited I responses in more than half the recorded cells.LY-marked tectal cells included five ganglionic cells, four pyramidal cells, two bipolar cells and two stellate cells.The ganglionic cells were mainly located in tectal layers Ⅲ and Ⅳ, whereas the others were in layer Ⅱ.It appears from both intracellular recordings and fluorescent markings that there is some
