CROSSED RECEPTIVE-FIELD COMPONENTS AND CROSSED DENDRITES IN CAT SACROCAUDAL DORSAL HORN

The hypothesis that sacrocaudal dorsal horn neurons with crossed recep tive field components on the tail have dendrites which cross to the co ntralateral dorsal horn was tested in a combined electrophysiological and morphological study. Dorsal horn cells in the sacrocaudal spinal c ord of anesthetized cats were penetrated with horseradish peroxidase-f illed microelectrodes. After mapping their low threshold mechanorecept ive fields, cells were iontophoretically injected with horseradish per oxidase. A sample of 16 well-stained cells was obtained in laminae III and IV. Cells with receptive fields crossing the dorsal midline of th e tail (n = 8) had somata in the lateral ipsilateral dorsal horn, and some of these cells (5/8) had dendrites which crossed to the lateral c ontralateral dorsal horn. Cells with receptive fields spanning the ven tral midline (n = 2) were located near the center of the fused dorsal horn, and one of these had bilateral dendrites in this region. Cells w ith receptive fields on the lateral tail, crossing neither the dorsal nor the ventral midline (n = 6), had cell bodies in the middle of the ipsilateral dorsal horn; half had only ipsilateral dendrites, and half had crossed dendritic branches. Although the relationship between cel l receptive field (RF) location (RF center, expressed as distance from tips of toes) and mediolateral location of the cell body was statisti cally significant, the correlation between crossed RF components and c rossed dendritic branches was not significant. (C) 1993 Wiley-Liss, In c.