Spatial correspondence between tactile projection patterns and the distribution of the antigenic purkinje cell markers anti-zebrin I and anti-zebrin II in the cerebellar folium crus IIa of the rat

We have compared the band-like distribution of the Purkinje cell-specific p olypeptides zebrin I and zebrin II with the spatial organization of tactile projections to crus IIa in the cerebellar hemisphere of the rat. Maps of t actile responses in the granular layer of the cerebellar hemispheres are fr actured into discontinuous regions, termed "patches". High-density micromap ping was used to identify specific patches and their boundaries within this fractured somatotopic map. In one series of experiments, medial and latera l boundaries of the large central ipsilateral upper lip-related patch were identified and labeled with either Fast Blue or India Ink. Following immuno cytochemical processing, the band-like distribution of immunostained Purkin je cells (zebrin-positive bands) and the identified patch boundaries were d igitized and reconstructed in three dimensions. Comparisons between these t wo features demonstrate a spatial correspondence between zebrin transitions and the boundaries of the electrophysiologically defined upper lip-related patch. In another series of experiments, we outlined the boundaries or cen ters of several smaller patches consistently located in the medial portion of the folium. Again, we found a correspondence between the distribution of granule cell layer tactile patches and the zebrin staining pattern. The correspondence between tactile projection patterns and molecular featur es demonstrated in the present study implies that there is a distinct and l argely fixed spatial pattern of organization in the cerebellar hemispheres. We discuss possible causal connections and developmental determinates, as well as the physiological significance of the correspondence between the tw o features. (C) 1999 IBRO. Published by Elsevier Science Ltd.