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J C Hedreen

Publications and source records attributed to J C Hedreen.

60 records · Page 4Linked to original sources
PubMed1981

Homotopic and heterotopic callosal afferents of caudal inferior parietal lobule in Macaca mulatta.

We have examined callosal-axon neurons giving rise to homotopic and heterotopic callosal projections to caudal inferior parietal lobule (area PG) in Macaca mulatta, identifying these neurons by means of retrograde axonal transport of horseradish peroxidase. The labeled neurons in the homotopic region occur predominantly in layers IIIB and V.A moderate number are also seen in layer VI, a smaller number of layer IV, and rare cells occur in layer II. These neurons occupy a region very similar in outline to the injection area, and though variable in density in the horizontal plane, are continuously distributed in this plane. The heterotopic neurons are seen in the contralateral cingulate gyrus, continuing caudally into medial parietal cortex, in the cortex of the superior temporal and occipitotemporal sulci, in the caudal superior temporal gyrus, and in the caudal inferior parietal lobule, behind the homotopic area. These same regions on the ipsilateral side contain labeled neurons of origin of ipsilateral association projections to area PG. For other ipsilateral labeling was found. A review of the literature on heterotopic callosal connections of a particular generalization of this conclusion: The callosal heterotopic connections of a particular cortical area are made with regions which on the ipsilateral side have associated connections with that area, though usually not with all of such regions.

Animals↗
PubMed1981

Retrograde and anterograde axonal transport demonstrated by intracerebral injection of a labeled protein-acylating agent.

Following injection of the tritium-labeled protein-acylating agent, N-succinimidyl propionate, into the neostriatum in rats, retrograde labeling of nigrostriatal cells in the pars compacta of the subtantia nigra and anterograde labeling of the striatonigral terminal field in the nigral pars reticulata were demonstrated by autoradiography, at 18 hr survival. Labeling of the corticopontine terminal field and of corticothalamic cell bodies in cortical layer 6 were also seen, deriving from corticofugal fibers of passage through the striatal injection site. In comparison, neostriatal injection of horseradish peroxidase was found to yield nigral cell and terminal field labeling, but the corticopontine terminal field was not labeled, and very few cortical cells in layer 6 were labeled. These results show that the retrograde and anterograde axonal transport of endogenous proteins can be profitably studied by this in vivo protein-acylating technique, and suggest that the method may prove useful as a connection-tracing technique, especially because of the novel attribute of labeling terminal fields by anterograde axonal transport following injections into white matter axonal bundles, with concomitant labeling od the cell bodies of origin of these axons.

Animals↗