Brain Research, 146 (1978) 145-150 ~) Elsevier/North-Holland Biomedical Press
145
Autoradiographic evidence for a discontinuous projection to the caudate nucleus from the centromedian nucleus in the cat
G. JAMES ROYCE Department of Anatomy, University of Wisconshl, Madison, Wise. 53706 (U.S.A.)
(Accepted November 10th, 1977)
There is a long history of experimental evidence which indicates that the intralaminar thalamic nuclei have extensive connections with the corpus striatum 2-4,7-t5. However, except for suggestions of broad topographic relationships, these studies have yielded little detailed information regarding the organization of these projections. For this reason, a series of experiments was initiated to define the details of these connections using the autoradiographic tracing method. During the course of this analysis, a striking new observation was made concerning the projection from the centromedian nucleus to the caudate nucleus. The present study reveals that, following injections of [3H]proline into the centromedian nucleus, there is transported protein within the caudate nucleus which is segregated into numerous patches, bands, semicircles and other configurations, many of which are highly distinctive and have a remarkable complexity. Five adult cats were used in this study. Injections of 0.5 4.0 #1 of 20-35 #Ci//~l of [3H]proline were stereotaxically placed into the centromedian nucleus (CM). These injections were made using a 26-gauge needle attached to a 10/~1 Hamilton syringe. Delivery of the precursor substance was controlled by a Harvard infusion pump connected to a series of oil filled tubing. Following survival periods of 7-14 days, the animals were perfused with 10 ~°/,,formalin, after which the brains were removed, stored in 30'~i sucrose-formalin and later cut on a freezing microtome at 40 #m. The sections were mounted on gelatinized slides, defatted and dipped in NTB-2 Kodak emulsion. The tissue was then stored for eight weeks in the dark at 4 °C, developed in D-19 and stained with cresyl violet. The distribution of label was mapped using an X-Y plotter. Several targets of the centromedian nucleus are apparent in all of the experiments analyzed in this study. These targets include: the rostral intralaminar nuclei, the thalamic reticular nucleus, the corpus striatum and the cerebral cortex. Since the patch-like projection to the caudate nucleus is so striking, it seems deserving of special mention and is therefore the principal topic of this communication. The other efferent projections from the centromedian nucleus will be presented in a subsequent report. Fig. 1 illustrates the distribution of label within the caudate (and surrounding
146
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145
Autoradiographic evidence for a discontinuous projection to the caudate nucleus from the centromedian nucleus in the cat
G. JAMES ROYCE Department of Anatomy, University of Wisconshl, Madison, Wise. 53706 (U.S.A.)
(Accepted November 10th, 1977)
There is a long history of experimental evidence which indicates that the intralaminar thalamic nuclei have extensive connections with the corpus striatum 2-4,7-t5. However, except for suggestions of broad topographic relationships, these studies have yielded little detailed information regarding the organization of these projections. For this reason, a series of experiments was initiated to define the details of these connections using the autoradiographic tracing method. During the course of this analysis, a striking new observation was made concerning the projection from the centromedian nucleus to the caudate nucleus. The present study reveals that, following injections of [3H]proline into the centromedian nucleus, there is transported protein within the caudate nucleus which is segregated into numerous patches, bands, semicircles and other configurations, many of which are highly distinctive and have a remarkable complexity. Five adult cats were used in this study. Injections of 0.5 4.0 #1 of 20-35 #Ci//~l of [3H]proline were stereotaxically placed into the centromedian nucleus (CM). These injections were made using a 26-gauge needle attached to a 10/~1 Hamilton syringe. Delivery of the precursor substance was controlled by a Harvard infusion pump connected to a series of oil filled tubing. Following survival periods of 7-14 days, the animals were perfused with 10 ~°/,,formalin, after which the brains were removed, stored in 30'~i sucrose-formalin and later cut on a freezing microtome at 40 #m. The sections were mounted on gelatinized slides, defatted and dipped in NTB-2 Kodak emulsion. The tissue was then stored for eight weeks in the dark at 4 °C, developed in D-19 and stained with cresyl violet. The distribution of label was mapped using an X-Y plotter. Several targets of the centromedian nucleus are apparent in all of the experiments analyzed in this study. These targets include: the rostral intralaminar nuclei, the thalamic reticular nucleus, the corpus striatum and the cerebral cortex. Since the patch-like projection to the caudate nucleus is so striking, it seems deserving of special mention and is therefore the principal topic of this communication. The other efferent projections from the centromedian nucleus will be presented in a subsequent report. Fig. 1 illustrates the distribution of label within the caudate (and surrounding
146
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