Abstract
We have examined whether individual cells of the zona incerta of the thalamus have widespread projections across the brain. Double injections of different coloured fluorescent latex beads (red or green) were made, in various combinations, into regions of neocortex, dorsal thalamus or brainstem of Sprague-Dawley rats. These regions were chosen since they have been shown previously to receive projections from the zona incerta. We also made injections of different coloured beads into different regions of these same brain centres (ie, distinct cortical areas or individual dorsal thalamic and brainstem nuclei). In general, our results show that cells of the zona incerta have projections limited to one of these brain centres only. We saw very few double-labelled incertal cells after double injections of different coloured latex beads into either the neocortex/dorsal thalamus, neocortex/brainstem or dorsal thalamus/brainstem. Further, we show that within each of these brain centres, the projection patterns of individual incertal cells is rather restricted, since double injections of different coloured beads into separate regions of the same centre resulted in few double-labelled incertal cells. Taken together, these results suggest a very clear specificity of projection among cells of the zona incerta. Thus, although the cells of the zona incerta receive a plethora of inputs from many sources, it appears that its cells have a very clear and focussed output to distinct regions of the brain.
Similar content being viewed by others
References
Beitz, A. J. (1989) Possible origin of glutamatergic projections to the midbrain periaqueductal grey and deep layer of the superior colliculus of the rat. Brain Research 23, 25-35.
Broberger, C., De Lecea, L. & Sutcliffe, J. G. (1998) Hypocretin/Orexin-and melanin-concentrating hormone-expressing cells form distinct populations in the rodent lateral hypothalamus: relationship to the neuropeptide Y and agouti gene-related protein systems. Journal of Comparative Neurology 402, 460-474.
Edwards, D. A. & Maillard, C. A. (1988) Subthalamic and mesencephalic locomotor regions: brain damage augments the importance of female movement for the display of sexual behaviour in male rats. Physiology and Behaviour 44, 803-809.
Elias, C. F., Saper, C. B., Maratos-Flier, E., Tritos, N., Lee, C., Kelly, J., Tatro, J. B., Hoffman, G. E., Ollman, M. M., Barsh, G. S., Sakurai, T., Yanagisawa, M. & Elmquist, J. K. (1998) Chemically defined projections linking the mediobasal hypothalamus and the lateral hypothalamic area. Journal of Comparative Neurology 402, 442-459.
Ficalora, A. S. & Mize, R. R. (1989) The neurones of the substantia nigra and the zona incerta which project to the cat superior colliculus are GABA immunoreactive: a double label study usingGABAimmunocytochemistry and lectin retrograde transport. Neuroscience 29, 567-581.
Gurdjian, E. S. (1927) The diencephalon of the albino rat. Studies on the brain of the rat. Journal of Comparative Neurology 173, 123-146.
Jones, E. G. (1985) The Thalamus. New York: Plenum Press.
Katz, L. C., Burkhalter, A. & Dreyer, W. J. (1984) Fluorescent latex microspheres as a retrograde neuronal marker for in vivo and in vitro studies of visual cortex. Nature 310, 498-500.
Kawana, E. & Watanabe, K. (1981) A cytoarchitectonic study of the zona incerta in the rat. Journal of Hirnforsch 22, 535-541.
Kim, U., Gregory, E. & Hall, W. C. (1992) Pathway from the zona incerta to the superior colliculus in the rat. Journal of Comparative Neurology 321, 555-575.
Kohler, C. & Swanson, L. W.(1984) Acetylcholinesterase-containing cells in the lateral hypothalamic area are immunoreactive for alpha-melanocyte stimulating hormone (alpha-MSH) and have cortical projections in the rat. Neuroscience Letters 49, 39-43.
Kohler. C., Haglund. L. & Swanson, L. W. (1984) A diffuse alpha MSH-immunoreactive projection to the hippocampus and spinal cord from individual neurones in the lateral hypothalamic area and zona incerta. Journal of Comparative Neurology 223, 501-514.
Kolmac, C. I. & Mitrofanis, J. (1997) Organisation of the reticular thalamic projection to the intralaminar and midline nuclei in rats. Journal of Comparative Neurology 377, 165-178.
Kolmac, C. I. & Mitrofanis, J. (1999) Distribution of various neurochemicals within zona incerta: an immunocytochemical and histochemical study. Anatomy and Embryology 199, 265-280.
Kolmac, C. I., Power, B. D. & Mitrofanis, J. (1998) Patterns of connections between zona incerta and brainstem in rats. Journal of Comparative Neurology 396, 544-555.
Kuzemensky, J. (1977) Contribution to the cytoarchitectonics of the zona incerta and ForelÕsfield in rodents. Folia Morphologica 25, 366-370.
Lin, R. C., Nicolelis, M. A., Schneider, J. S. & Chapin, J. K. (1990) A major GABAergic pathway from zona incerta to neocortex. Science 248, 1553-1556.
Lin, R. C., Nicolelis, M. A. & Chapin, J. K. (1997) Topographic and laminar organisations of the incertocortical pathways in rats. Neuroscience 81, 641-651.
Ma, T. P., Hu, X.-J., Anavi, Y. & Rafols, J. A. (1992) Organisation of the zona incerta in the macaque: a Nissl and Golgi study. Journal of Comparative Neurology 320, 273-290.
May, P. J., Sun, W. & Halls, W. C. (1997) Reciprocal connections between the zona incerta and the pretectum and superior colliculus of the cat. Neuroscience 77, 1091-1114.
Mogenson, G. J., Swanson, L. W. & Wu, M. (1985) Evidence that projections from substantia innominata to zona incerta and mesencephalic locomotor region contribute to locomotor activity. Brain Research 334, 65-76.
Nicolelis, M. A., Chapin, J. K. & Lin, R. C. (1992) Somatotopic maps within the zona incerta relay parallel GABAergic somatosensory pathways to the neocortex, superior colliculus and brainstem. Brain Research 577, 134-141.
Nicolelis, M. A., Chapin, J. K. & Lin, R. C. (1995) Development of direct GABAergic projections from the zona incerta to the somatosensory cortex of the rat. Neuroscience 65, 609-631.
Paxinos, G. & Watson, C. J. (1986) The Rat Brain in Stereotaxic Coordinates, 2nd edn. Academic Press.
Power, B. D. & Mitrofanis, J. (1999) Evidence for extensive inter-connections within the zona incerta in rats. Neuroscience Letters.
Power, B. D., Kolmac, C. I. & Mitrofanis, J. (1999) Evidence for a large projection from the zona incerta to the dorsal thalamus. Journal of Comparative Neurology 404, 554-565.
Ricardo, J. A. (1981) Efferent connections of the subthalamic region in the rat. II. The zona incerta. Brain Research 214, 43-60.
Roger, M. & Cadusseau, J. (1985) Afferents to the zona incerta in the rat: a combined retrograde and anterograde study. Journal of Comparative Neurology 241, 480-492.
Romanowski, C. A. J., Mitchell, I. J. & Crossman, A. R. (1985) The organisation of the different projections of the zona incerta. Journal of Anatomy 143, 75-95.
Saper, C. B. (1985) Organisation of cerebral cortical afferent systems in the rat. II. Hypothalamo-cortical projections. Journal of Comparative Neurology 237, 21-46.
Saper, C. B., Akil, H. & Watson, S. J. (1986) Lateral hypothalamic innervation of the cerebral cortex: Immunoreactive staining for a peptide resembling but immunohistochemically distinct from pituitary/arcuate ®-melanocyte stimulating hormone. Brain Research Bulletin 16, 107-120.
Swanson, L. W. (1992) Brain Maps: Structure of the Rat Brain. Netherlands: Elsevier.
Vaccaro, T. M. & Mitrofanis, J.(1997) Does the reticular thalamic nucleus project to the midbrain? Journal of Neurocytology 26, 223-239.
Wagner, C. K., Eaton, M. J., Moore, K. E. & Lookingland, K. J. (1995) Efferent projections from the region of the medial zona incerta containing A13 dopaminergic neurones: a PHA-L anterograde tracttracing study in the rat. Brain Research 677, 229-237.
Watanabe, K. & Kawana, E. (1982) The cells of origin of the incerto-fugal projections to the tectum, thalamus, tegmentum and spinal cord in the rat: a study using autoradiographic and horseradish peroxidase methods. Neuroscience 10, 2389-2406.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Power, B.D., Mitrofanis, J. Specificity of projection among cells of the zona incerta. J Neurocytol 28, 481–493 (1999). https://doi.org/10.1023/A:1007005105679
Issue Date:
DOI: https://doi.org/10.1023/A:1007005105679