COLOCALIZATION OF PARVALBUMIN, CALRETININ AND CALBINDIN D-28K IN HUMAN CORTICAL AND SUBCORTICAL VISUAL STRUCTURES

Several studies have demonstrated that three calcium-binding proteins parvalbumin (PV); calbindin D-28k (CB) and calretinin (CR) mark distin ct subsets of cortical interneurons. This study demonstrates, in corti cal and subcortical visual structures, the coexistence of two calcium- binding proteins in some neuronal subpopulations. The human Visual cor tex (VC), lateral geniculate nucleus (LGN), lateral inferior pulvinar (LIP) and superior colliculus (SC) were examined by a double-labelling immunocylochemical technique. The VC showed mostly separate populatio ns of PV, CB and CR immunoreactive (-ir) interneurons, but also small populations of double-stained PV + CR and CR + CB neurons, while PV CB neurons were less frequent. An average of 2.5% of the immunoreactiv e neurons were double-stained for PV + CR and 7.1% for CR + CB in area 17, while this percentage was slightly higher in association area 18 (3.3 and 7.4%, respectively). In the LGN and LIP, double-stained neuro ns were scarce, but in the fibre capsule of these nuclei, as well as i n the optic radiation (OR) and white matter underlying area 17, both d ouble-stained PV + CR or CR + CB and separate populations of PV-ir, CB -ir and CR-ir neurons and fibres were observed. Unlike the thalamic re gions, the SC showed some double-stained PV + CR and CR + CB neurons, scattered both in the superficial and deep layers. These findings are discussed in the light of similar observations recently reported from other regions of the human brain. (C) 1997 Elsevier Science B.V.