The distribution of calbindin, calretinin and parvalbumin immunoreactivityin the human thalamus

Calcium-binding proteins show a heterogeneous distribution in the mammalian central nervous system and are useful markers for identifying neuronal pop ulations. The distribution of the three major calcium-binding proteins - ca lbindin-D28k (calbindin), calretinin and parvalbumin - has been investigate d in eight neurologically normal human thalami using standard immunohistoch emical techniques. Most thalamic nuclei show immunoreactive cell bodies for at least two of the three calcium-binding proteins; the only nucleus showi ng immunoreactivity for one calcium-binding protein is the centre median nu cleus (CM) which is parvalbumin-positive. Overall, the calcium-binding prot eins show a complementary staining pattern in the human thalamus. In genera l terms, the highest density of parvalbumin staining is in the component nu clei of the ventral nuclear group (i.e. in the ventral anterior, ventral la teral and ventral posterior nuclear complexes) and in the medial and latera l geniculate nuclear groups. Moderate densities of parvalbumin staining are also present in regions of the mediodorsal nucleus (MD). By contrast, calb indin and calretinin immunoreactivity both show a similar distribution of d ense staining in the thalamus which appears to complement the pattern of in tense parvalbumin staining. That is, calbindin and calretinin staining is m ost dense in the rostral intralaminar nuclear group and in the patchy regio ns of the MD which show very low levels of parvalbumin staining. However, c albindin and calretinin also show low levels of staining in the ventral nuc lear complex and in the medial and lateral geniculate bodies which overlaps with the intense parvalbumin staining in these reg;ions. These results sho w that the calcium-binding proteins are heterogeneously distributed in a co mplementary fashion within the nuclei of the human thalamus. They provide f urther support for the concept recently proposed by Jones (Jones, E.G., 199 8. Viewpoint: the core and matrix of thalamic organization. Neuroscience 85 , 331-345) that the primate thalamus comprises of a matrix of calbindin imm unoreactive cells and a superimposed core of parvalbumin immunoreactive cel ls which may have differential patterns of cortical projections. (C) 2000 E lsevier Science B.V. All rights reserved.