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Direct projections from the substantia nigra to the posterior thalamic regions in the cat
Brain Research, 309 (1984) 143-146 Elsevier
143
BRE 20336
Short Communications
Direct projections from the substantia nigra to the posterior thalamic regions in the cat MASAHIKO TAKADA, KAZUO ITOH, YUKIHIKO YASUI, TETSUO SUGIMOTO and NOBORU MIZUNO
Department of Anatomy (1stDivision), Facultyof Medicine, Kyoto University, Kyoto 606 (Japan) (Accepted April 24th, 1984)
Key words: substantia nigra - - LP - - suprageniculate nucleus - - HRP - - cat
The substantia nigra (SN) of the cat was shown, by the anterograde and retrograde horseradish peroxidase methods, to contain neurons which send their axons to the caudomedial portions of the suprageniculate nucleus and/or lateroposterior nucleus of the thalamus; these neurons were located in the restricted region in the lateral part of the SN, which corresponds to the pars lateralis of the SN. The substantia nigra (SN) of the cat is composed of 3 portions; pars reticularis (SNpr), pars compacta (SNpc) and pars lateralis (SNpl)1,2,6,8. The SNpl lies in the lateralmost part of the SN, and extends from the level of the caudal border of the mammillary body to the level of the caudal border of the root fibers of the oculomotor nerve. The present report deals with hitherto unknown direct projections from the SNpl to the posterior thalamic regions in the cat. In 12 cats anesthetized with sodium pentobarbital (35 mg/kg body wt., i.p.), single injections of 0.5% W G A - H R P (Sigma) in 0.1 M Tris buffer (pH 7.9), or 20% H R P (Toyobo, Grade-l-C) in 0.9% saline containing 0.4% poly-L-ornithine, were made stereotaxically into the SN, or the lateroposterior (LP) and suprageniculate (Sg) nuclei of the thalamus (Figs. 1a-d), through a glass micropipette (internal tip diameter: 5-25 pm) by pulsing a 1 . 0 - 4 . 0 / t A positive current (200 ms duration, 2.5 cycle/s) for 20-60 min. After 30-40 h, the cats were reanesthetized deeply, and perfused transcardially with 3 liters of 0.8% formalin in 0.1 M phosphate buffer (pH 7.3), followed by 2 liters of the same buffer containing 10% sucrose. The brains were removed immedi-
ately, saturated with the same buffer containing 25% sucrose at 4 °C. Subsequently, the brains were cut serially at 60/am thickness in the coronal plane on a freezing microtome. The sections were treated according to the tetramethylbenzidine method 5 or the diaminobenzidine methodT, mounted onto gelatin-coated slides, and counterstained with 0.3% neutral red or 0.5 % cresyl violet. In 3 cats injected with W G A - H R P into the lateral portions of the SN (Cl15, C120 in Fig. lb, and Cl18 in Fig. ld), clusters of possible axon terminals labeled anterogradely with the enzyme were distributed ipsilaterally to the intermediate and deep layers of the superior colliculus (SC), in addition to the globus pallidus, and thalamic nuclei, such as the ventroanterior, ventrolateral, ventromedial, submedius, centrolateral, paracentral, centromedial and subparafascicular nuclei, and paralamellar portion of the mediodorsal nucleus. In one of these cats (C120), in which W G A - H R P injection was centered on the SNpl (stereotaxic coordinates: A 5 . 0 - A 6.5) (Figs. lb and 2a), labeled axon terminals were further found ipsilaterally in the caudomedial portions of the LP and Sg (stereotaxic coordinates: A 5 . 5 - A
Correspondence: N. Mizuno, Department of Anatomy, Faculty of Medicine, Kyoto University, Kyoto, 606, Japan. 0006-8993/84/$03.00 t~ 1984 Elsevier Science Publishers B.V.
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58
/
5
/
41
Fig. 1. Upper row (a-d): diagrams showing the injection sites of WGA-HRP (stippled areas) or HRP (blackened areas) in 12 cats. Middle row: projection drawings of frontal sections through the mesodiencephalic regions of C120, showing the site of WGA-HRP injection in the SNpl (stippled areas), and distribution of anterogradely-labeled possible axon terminals (fine dots) and retrogradely-labeled neuronal cell bodies (small filled circles). Lower row: projection drawings of frontal sections through the mesodiencephalic regions of C62, showing the site of HRP injection (blackened areas) in the caudomedial part of the LP, and distribution of retrogradelylabeled neuronal cell bodies (small filled circles) in the SNpl. The numbers in the middle and lower rows indicate the position of the sections in the series of serial sections of 60/~m thickness. CM, centre median nucleus; CP, cerebral peduncle; D, Darkschewitsch's nucleus; d, deep layers of the SC; DR, dorsal raphe nucleus; EW, Edinger-Westphal's nucleus; i, intermediate layers of the SC; IC, interstitial nucleus of Cajal; MG, medial geniculate nucleus; O, oculomotor nucleus; Pf, parafascicular nucleus; Pt, pretectum; Pul, pulvinar nucleus; R, red nucleus; s, superficial layers of the SC; T, trochlear nucleus.
145 6.5) (middle row of Fig. 1). Since no labeled neuronal cell bodies were found in the SC, the possibility that transsynaptic transport via the SC was responsible for the terminal labeling in the LP and Sg could be excluded. In 2 other cats (Cl15 and Cl18), no labeled axon terminals were found in the Sg and LP; the injection site in Cl15 was located in the SNpr medial to the SNpl (Fig. lb), and the injection site in Cl18 was located in the lateral region of the SNpr at caudal levels where the SNpl is not present (Fig. ld). In 1 cat which was injected with W G A - H R P more caudolaterally than in C120 (Cl12 in Fig. lc), labeled neuronal cell bodies were seen in the inferior colliculus, but no labeled axon terminals were found in the SC, LP and Sg. In 4 of 8 cats injected with H R P into the regions around the caudomedial regions of the Sg and LP (Figs. l a - c and 2b), HRP-labeled neuronal cell bodies were seen ipsilaterally in the SNp11,2.6.8 (C60, C62, C66 and C67). No spread of injected H R P along the glass micropipette was noted in these cats (Fig. 2b). The pattern of distribution of HRP-labeled neuronal cell bodies in the SNpl in a representative cat (C62) is shown in the lower row of Fig. 1. In the 4 cats with HRP-iabeled neuronal cell bodies in the SNpl, labeled neuronal cell bodies were further seen ipsilaterally in the SC and the reticular nucleus of the thalamus; labeled neuronal cell bodies in the SC were located mainly in the superficial layers, and additionally in the deep layers in C60 and C62, and chiefly in the intermediate and deep layers in C66 and C67. In 4 other cats which were injected with H R P more rostrally or laterally in the LP or Sg (C63, C70, C73 and C74), HRP-labeled neuronal cell bodies were also found in the SC and the reticular nucleus of the thalamus, but not in the SN. The present study indicates that the SNpl of the cat sends afferent fibers to the caudomedial regions in the LP and Sg, as well as to the deep and intermediate layers of the SC. The data further suggest that the SNpl-recipient regions in the LP and Sg receive afferent fibers, respectively, from the superficial layers or intermediate and deep layers of the SC. The SC of the mammals is functionally composed of 2 divisions: a superficial division, implicated in visual processing, and a deeper division, concerned with orienting movements of the head and eyes in response to stimuli (for review, see ref. 9). Therefore, if the
~f
a
•
_ . _
Fig. 2. Photomicrographs of frontal sections, showing the injection site of WGA-HRP in the SNpl of C120 (a), and that of HRP in the LP of C62 (b). An arrow in (a) points to the track of a glass micropipette. Scale bar = 1 mm. Abbreviations are as in Fig. 1. SNpl-recipient regions in the LP-Sg are really the relay portions for signals via the SC, the SNpl neurons projecting to these LP, Sg and/or SC regions may constitute links in the neuronal circuits underlying visual processing and/or regulation of orienting movements of the head and eyes. Recently Hikosaka and Wurtz3, 4 observed in the rhesus monkey that some neurons in the lateral part of the SNpr changed their activity in response to saccade eye movements, and that these neurons sent their axons to the intermediate, and possibly deep layers of the SC. Judging from their data (especially from Fig. 3 of ref. 3), some of the SN neurons which respond in relation to visual stimuli or saccadic eye movements in the rhesus monkey appear to be located in the lateral SN regions which may correspond to the SNpl in the cat.
146 The photographic help of Mr. Akira Uesugi and the support of the Niwa Medical Research Foundation are gratefully acknowledged. This work has been supported in part by G r a n t - i n - A i d for Special
1 Berman, A. L., The Brain Stem o f the Cat. A Cytoarchitectonic Atlas with Stereotaxic Coordinates, The University of WisconsinPress, Madison, 1968. 2 Brown, J. O., The nuclear pattern of the non-tectal portions of the midbrain and isthmus in the dog and cat, J. comp. Neurol., 78 (1943) 365-405. 3 Hikosaka, O. and Wurtz, R. H., Visual and oculomotor functions of monkey substantia nigra pars reticulata. I. Relation of visual and auditory responses to saccades, J. Neurophysiol., 49 (1983) 1230-1253. 4 Hikosaka, O. and Wurtz, R. H., Visual and oculomotor functions of monkey substantia nigra pars reticulata. IV. Relation of substantia nigra to superior coUiculus, J. Neurophysiol., 49 (1983) 1285-1301. 5 Mesulam, M.-M., Tetramethyl benzidine for horseradish peroxidase neurohistochemistry: a non-carcinogenic blue re-
Project Research
Nos.
56121006, 57114006 and
58106006, and G r a n t - i n - A i d for Scientific Research No. 57440020 from the Ministry of Education, Science and Culture of Japan.
action-product with superior sensitivity for visualizing neural afferents and efferents, J. Histochem. Cytochem., 26 (1978) 106-117. 6 Rioch, D. M., Studies on the diencephalon of carnivora. Part II: Certain nuclear configurations and fiber connections of the subthalamus and midbrain of the dog and cat, J. comp. Neurol., 49 (1929) 121-153. 7 Streit, P. and Reubi, J. C., A new sensitive staining method for axonally transported horseradish peroxidase (HRP) in the pigeon visual system, Brain Research, 126 (1977) 530-537. 8 Taber, E., The cytoarchitecture of the brain stem of the cat. I. Brain stem nuclei of cat, J. comp. Neurol., 116 (1961) 27-70. 9 Wurtz, R. H. and Albano, J. E., Visuo-motor function of the primate superior colliculus, Ann. Rev. Neurosci., 3 (1980) 189-226.
143
BRE 20336
Short Communications
Direct projections from the substantia nigra to the posterior thalamic regions in the cat MASAHIKO TAKADA, KAZUO ITOH, YUKIHIKO YASUI, TETSUO SUGIMOTO and NOBORU MIZUNO
Department of Anatomy (1stDivision), Facultyof Medicine, Kyoto University, Kyoto 606 (Japan) (Accepted April 24th, 1984)
Key words: substantia nigra - - LP - - suprageniculate nucleus - - HRP - - cat
The substantia nigra (SN) of the cat was shown, by the anterograde and retrograde horseradish peroxidase methods, to contain neurons which send their axons to the caudomedial portions of the suprageniculate nucleus and/or lateroposterior nucleus of the thalamus; these neurons were located in the restricted region in the lateral part of the SN, which corresponds to the pars lateralis of the SN. The substantia nigra (SN) of the cat is composed of 3 portions; pars reticularis (SNpr), pars compacta (SNpc) and pars lateralis (SNpl)1,2,6,8. The SNpl lies in the lateralmost part of the SN, and extends from the level of the caudal border of the mammillary body to the level of the caudal border of the root fibers of the oculomotor nerve. The present report deals with hitherto unknown direct projections from the SNpl to the posterior thalamic regions in the cat. In 12 cats anesthetized with sodium pentobarbital (35 mg/kg body wt., i.p.), single injections of 0.5% W G A - H R P (Sigma) in 0.1 M Tris buffer (pH 7.9), or 20% H R P (Toyobo, Grade-l-C) in 0.9% saline containing 0.4% poly-L-ornithine, were made stereotaxically into the SN, or the lateroposterior (LP) and suprageniculate (Sg) nuclei of the thalamus (Figs. 1a-d), through a glass micropipette (internal tip diameter: 5-25 pm) by pulsing a 1 . 0 - 4 . 0 / t A positive current (200 ms duration, 2.5 cycle/s) for 20-60 min. After 30-40 h, the cats were reanesthetized deeply, and perfused transcardially with 3 liters of 0.8% formalin in 0.1 M phosphate buffer (pH 7.3), followed by 2 liters of the same buffer containing 10% sucrose. The brains were removed immedi-
ately, saturated with the same buffer containing 25% sucrose at 4 °C. Subsequently, the brains were cut serially at 60/am thickness in the coronal plane on a freezing microtome. The sections were treated according to the tetramethylbenzidine method 5 or the diaminobenzidine methodT, mounted onto gelatin-coated slides, and counterstained with 0.3% neutral red or 0.5 % cresyl violet. In 3 cats injected with W G A - H R P into the lateral portions of the SN (Cl15, C120 in Fig. lb, and Cl18 in Fig. ld), clusters of possible axon terminals labeled anterogradely with the enzyme were distributed ipsilaterally to the intermediate and deep layers of the superior colliculus (SC), in addition to the globus pallidus, and thalamic nuclei, such as the ventroanterior, ventrolateral, ventromedial, submedius, centrolateral, paracentral, centromedial and subparafascicular nuclei, and paralamellar portion of the mediodorsal nucleus. In one of these cats (C120), in which W G A - H R P injection was centered on the SNpl (stereotaxic coordinates: A 5 . 0 - A 6.5) (Figs. lb and 2a), labeled axon terminals were further found ipsilaterally in the caudomedial portions of the LP and Sg (stereotaxic coordinates: A 5 . 5 - A
Correspondence: N. Mizuno, Department of Anatomy, Faculty of Medicine, Kyoto University, Kyoto, 606, Japan. 0006-8993/84/$03.00 t~ 1984 Elsevier Science Publishers B.V.
144
C12~0 ~
58
/
5
/
41
Fig. 1. Upper row (a-d): diagrams showing the injection sites of WGA-HRP (stippled areas) or HRP (blackened areas) in 12 cats. Middle row: projection drawings of frontal sections through the mesodiencephalic regions of C120, showing the site of WGA-HRP injection in the SNpl (stippled areas), and distribution of anterogradely-labeled possible axon terminals (fine dots) and retrogradely-labeled neuronal cell bodies (small filled circles). Lower row: projection drawings of frontal sections through the mesodiencephalic regions of C62, showing the site of HRP injection (blackened areas) in the caudomedial part of the LP, and distribution of retrogradelylabeled neuronal cell bodies (small filled circles) in the SNpl. The numbers in the middle and lower rows indicate the position of the sections in the series of serial sections of 60/~m thickness. CM, centre median nucleus; CP, cerebral peduncle; D, Darkschewitsch's nucleus; d, deep layers of the SC; DR, dorsal raphe nucleus; EW, Edinger-Westphal's nucleus; i, intermediate layers of the SC; IC, interstitial nucleus of Cajal; MG, medial geniculate nucleus; O, oculomotor nucleus; Pf, parafascicular nucleus; Pt, pretectum; Pul, pulvinar nucleus; R, red nucleus; s, superficial layers of the SC; T, trochlear nucleus.
145 6.5) (middle row of Fig. 1). Since no labeled neuronal cell bodies were found in the SC, the possibility that transsynaptic transport via the SC was responsible for the terminal labeling in the LP and Sg could be excluded. In 2 other cats (Cl15 and Cl18), no labeled axon terminals were found in the Sg and LP; the injection site in Cl15 was located in the SNpr medial to the SNpl (Fig. lb), and the injection site in Cl18 was located in the lateral region of the SNpr at caudal levels where the SNpl is not present (Fig. ld). In 1 cat which was injected with W G A - H R P more caudolaterally than in C120 (Cl12 in Fig. lc), labeled neuronal cell bodies were seen in the inferior colliculus, but no labeled axon terminals were found in the SC, LP and Sg. In 4 of 8 cats injected with H R P into the regions around the caudomedial regions of the Sg and LP (Figs. l a - c and 2b), HRP-labeled neuronal cell bodies were seen ipsilaterally in the SNp11,2.6.8 (C60, C62, C66 and C67). No spread of injected H R P along the glass micropipette was noted in these cats (Fig. 2b). The pattern of distribution of HRP-labeled neuronal cell bodies in the SNpl in a representative cat (C62) is shown in the lower row of Fig. 1. In the 4 cats with HRP-iabeled neuronal cell bodies in the SNpl, labeled neuronal cell bodies were further seen ipsilaterally in the SC and the reticular nucleus of the thalamus; labeled neuronal cell bodies in the SC were located mainly in the superficial layers, and additionally in the deep layers in C60 and C62, and chiefly in the intermediate and deep layers in C66 and C67. In 4 other cats which were injected with H R P more rostrally or laterally in the LP or Sg (C63, C70, C73 and C74), HRP-labeled neuronal cell bodies were also found in the SC and the reticular nucleus of the thalamus, but not in the SN. The present study indicates that the SNpl of the cat sends afferent fibers to the caudomedial regions in the LP and Sg, as well as to the deep and intermediate layers of the SC. The data further suggest that the SNpl-recipient regions in the LP and Sg receive afferent fibers, respectively, from the superficial layers or intermediate and deep layers of the SC. The SC of the mammals is functionally composed of 2 divisions: a superficial division, implicated in visual processing, and a deeper division, concerned with orienting movements of the head and eyes in response to stimuli (for review, see ref. 9). Therefore, if the
~f
a
•
_ . _
Fig. 2. Photomicrographs of frontal sections, showing the injection site of WGA-HRP in the SNpl of C120 (a), and that of HRP in the LP of C62 (b). An arrow in (a) points to the track of a glass micropipette. Scale bar = 1 mm. Abbreviations are as in Fig. 1. SNpl-recipient regions in the LP-Sg are really the relay portions for signals via the SC, the SNpl neurons projecting to these LP, Sg and/or SC regions may constitute links in the neuronal circuits underlying visual processing and/or regulation of orienting movements of the head and eyes. Recently Hikosaka and Wurtz3, 4 observed in the rhesus monkey that some neurons in the lateral part of the SNpr changed their activity in response to saccade eye movements, and that these neurons sent their axons to the intermediate, and possibly deep layers of the SC. Judging from their data (especially from Fig. 3 of ref. 3), some of the SN neurons which respond in relation to visual stimuli or saccadic eye movements in the rhesus monkey appear to be located in the lateral SN regions which may correspond to the SNpl in the cat.
146 The photographic help of Mr. Akira Uesugi and the support of the Niwa Medical Research Foundation are gratefully acknowledged. This work has been supported in part by G r a n t - i n - A i d for Special
1 Berman, A. L., The Brain Stem o f the Cat. A Cytoarchitectonic Atlas with Stereotaxic Coordinates, The University of WisconsinPress, Madison, 1968. 2 Brown, J. O., The nuclear pattern of the non-tectal portions of the midbrain and isthmus in the dog and cat, J. comp. Neurol., 78 (1943) 365-405. 3 Hikosaka, O. and Wurtz, R. H., Visual and oculomotor functions of monkey substantia nigra pars reticulata. I. Relation of visual and auditory responses to saccades, J. Neurophysiol., 49 (1983) 1230-1253. 4 Hikosaka, O. and Wurtz, R. H., Visual and oculomotor functions of monkey substantia nigra pars reticulata. IV. Relation of substantia nigra to superior coUiculus, J. Neurophysiol., 49 (1983) 1285-1301. 5 Mesulam, M.-M., Tetramethyl benzidine for horseradish peroxidase neurohistochemistry: a non-carcinogenic blue re-
Project Research
Nos.
56121006, 57114006 and
58106006, and G r a n t - i n - A i d for Scientific Research No. 57440020 from the Ministry of Education, Science and Culture of Japan.
action-product with superior sensitivity for visualizing neural afferents and efferents, J. Histochem. Cytochem., 26 (1978) 106-117. 6 Rioch, D. M., Studies on the diencephalon of carnivora. Part II: Certain nuclear configurations and fiber connections of the subthalamus and midbrain of the dog and cat, J. comp. Neurol., 49 (1929) 121-153. 7 Streit, P. and Reubi, J. C., A new sensitive staining method for axonally transported horseradish peroxidase (HRP) in the pigeon visual system, Brain Research, 126 (1977) 530-537. 8 Taber, E., The cytoarchitecture of the brain stem of the cat. I. Brain stem nuclei of cat, J. comp. Neurol., 116 (1961) 27-70. 9 Wurtz, R. H. and Albano, J. E., Visuo-motor function of the primate superior colliculus, Ann. Rev. Neurosci., 3 (1980) 189-226.