Cortical projections to the superior colliculus in tree shrews (Tupaia belangeri)
Article first published online: 18 MAR 2013
Copyright © 2012 Wiley Periodicals, Inc.
Journal of Comparative Neurology
Volume 521, Issue 7, pages 1614–1632, 1 May 2013
How to Cite
Baldwin, M. K.L., Wei, H., Reed, J. L., Bickford, M. E., Petry, H. M. and Kaas, J. H. (2013), Cortical projections to the superior colliculus in tree shrews (Tupaia belangeri). J. Comp. Neurol., 521: 1614–1632. doi: 10.1002/cne.23249
- Issue published online: 18 MAR 2013
- Article first published online: 18 MAR 2013
- Accepted manuscript online: 1 NOV 2012 08:52AM EST
- Manuscript Accepted: 25 OCT 2012
- Manuscript Revised: 10 JUL 2012
- Manuscript Received: 27 APR 2012
- National Eye Institute. Grant Numbers: RO1 EY-02686, RO1 EY-016155, CORE grants P30 EY-008126
- superior colliculus;
The visuomotor functions of the superior colliculus depend not only on direct inputs from the retina, but also on inputs from neocortex. As mammals vary in the areal organization of neocortex, and in the organization of the number of visual and visuomotor areas, patterns of corticotectal projections vary. Primates in particular have a large number of visual areas projecting to the superior colliculus. As tree shrews are close relatives of primates, and they are also highly visual, we studied the distribution of cortical neurons projecting to the superior colliculus by injecting anatomical tracers into the colliculus. Since projections from visuotopically organized visual areas are expected to match the visuotopy of the superior colliculus, injections at different retinotopic locations in the superior colliculus provide information about the locations and organization of topographic areas in extrastriate cortex. Small injections in the superior colliculus labeled neurons in locations within areas 17 (V1) and 18 (V2) that are consistent with the known topography of these areas and the superior colliculus. In addition, the separate locations of clusters of labeled cells in temporal visual cortex provide evidence for five or more topographically organized areas. Injections that included deeper layers of the superior colliculus also labeled neurons in medial frontal cortex, likely in premotor cortex. Only occasional labeled neurons were observed in somatosensory or auditory cortex. Regardless of tracer injection location, we found that, unlike primates, a substantial projection to the superior colliculus from posterior parietal cortex is not a characteristic of tree shrews. J. Comp. Neurol. 521:1614–1632, 2013. © 2012 Wiley Periodicals, Inc.