Our preceding papers have shown that the nucleus isthmi (NI) is a secondary visual center in anuran amphibians. We, using HRP tracing and Golgi-Cox impregna-
Electrophysiological studies have shown that acetylcholine may be one of the neurotransmitters in the nucleus isthmi (NI) of amphibians and reptiles, but little (in amphibians) or nothing (in reptiles) is known about ...Electrophysiological studies have shown that acetylcholine may be one of the neurotransmitters in the nucleus isthmi (NI) of amphibians and reptiles, but little (in amphibians) or nothing (in reptiles) is known about the distribution of its hydrolase,acetylcholinesterase (AChE), within NI. However, abundant AChE is a necessary con-展开更多
The lacertilian optic tectum (OT) plays an important role in sensorimotor integration; while the nucleus isthmus (NI) is a secondary visual center closely connected with OT. Although Butler and Ebbesson have reported ...The lacertilian optic tectum (OT) plays an important role in sensorimotor integration; while the nucleus isthmus (NI) is a secondary visual center closely connected with OT. Although Butler and Ebbesson have reported OT cell types of the tegu lizard, so far we have not yet seen any report concerning cell morphology in the lacerti-展开更多
Ⅰ. INTRODUCTION In anuran amphibians, the tegmentum mesencephali is mainly occupied by sensory centers, e.g. the torus semicircularis being an auditory center, the nucleus opticus tegmenti associated with optokinetic...Ⅰ. INTRODUCTION In anuran amphibians, the tegmentum mesencephali is mainly occupied by sensory centers, e.g. the torus semicircularis being an auditory center, the nucleus opticus tegmenti associated with optokinetic nystagmus, and nucleus isthmi considered as a secondary visual center, However, very little is known about physiological significance of the rest part of the tegmentum. Anatomical findings have shown that the lateral tegmentum is connected with the optic tectum, telencephalic striatum展开更多
Our previous study on frogs has indicated that a restricted part of the frog’s visual system is the nucleus isthmi (NI), in which there is a retinotopic map, and isthmic binocular units are found in NI (Wang, S. J. e...Our previous study on frogs has indicated that a restricted part of the frog’s visual system is the nucleus isthmi (NI), in which there is a retinotopic map, and isthmic binocular units are found in NI (Wang, S. J. et al., Neurosei. Letters, 23(1981), 37—41).展开更多
The isthmic nucleus (IN) in the frog is a midbrain structure, located at the border between mesencephalic tegmentum and cerebellum. In recent years several anatomical, physiological and histochemical studies have show...The isthmic nucleus (IN) in the frog is a midbrain structure, located at the border between mesencephalic tegmentum and cerebellum. In recent years several anatomical, physiological and histochemical studies have shown that IN is a part of the frog visual system. We investigated visual responses of single units and a visual field topography in IN of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
文摘Our preceding papers have shown that the nucleus isthmi (NI) is a secondary visual center in anuran amphibians. We, using HRP tracing and Golgi-Cox impregna-
文摘Electrophysiological studies have shown that acetylcholine may be one of the neurotransmitters in the nucleus isthmi (NI) of amphibians and reptiles, but little (in amphibians) or nothing (in reptiles) is known about the distribution of its hydrolase,acetylcholinesterase (AChE), within NI. However, abundant AChE is a necessary con-
文摘The lacertilian optic tectum (OT) plays an important role in sensorimotor integration; while the nucleus isthmus (NI) is a secondary visual center closely connected with OT. Although Butler and Ebbesson have reported OT cell types of the tegu lizard, so far we have not yet seen any report concerning cell morphology in the lacerti-
文摘Ⅰ. INTRODUCTION In anuran amphibians, the tegmentum mesencephali is mainly occupied by sensory centers, e.g. the torus semicircularis being an auditory center, the nucleus opticus tegmenti associated with optokinetic nystagmus, and nucleus isthmi considered as a secondary visual center, However, very little is known about physiological significance of the rest part of the tegmentum. Anatomical findings have shown that the lateral tegmentum is connected with the optic tectum, telencephalic striatum
文摘Our previous study on frogs has indicated that a restricted part of the frog’s visual system is the nucleus isthmi (NI), in which there is a retinotopic map, and isthmic binocular units are found in NI (Wang, S. J. et al., Neurosei. Letters, 23(1981), 37—41).
文摘The isthmic nucleus (IN) in the frog is a midbrain structure, located at the border between mesencephalic tegmentum and cerebellum. In recent years several anatomical, physiological and histochemical studies have shown that IN is a part of the frog visual system. We investigated visual responses of single units and a visual field topography in IN of
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.
