Dendritic trees and cutaneous receptive fields of adjacent spinocervical tract neurones in the cat.

Abstract

The relationship between the dendritic trees and the receptive fields of adjacent spinocervical tract neurons was studied using the intracellular injection of horseradish peroxidase in chloralose-anesthetized, paralysed, cats. Fourteen pairs of neurons were successfully stained, and the receptive fields of 12 paris were also defined. Five of the pairs were ''rostrocaudal pairs'', i.e., in line within .+-. 50 .mu.m of each other in the rostrocaudal axis of the cord. Nine of the pairs were ''mediolateral pairs'', i.e., in line within .+-. 50 .mu.m of each other in the mediolateral axis of the cord. For 12 pairs of stained neurons, for which the receptive fields were described, a correspondence was found between the organization of their dendritic trees and their receptive fields. All 5 rostrocaudal pairs of neurons had interdigitating dendritic trees together with overlapping receptive fields. Of the 7 mediolateral pairs, 4 had receptive fields which overlapped and interdigitating dendritic trees. The remaining 3 had separate receptive fields and non-interdigitating dendritic trees. The results are discussed in relation to previous work on thecolumnar organization of the receptive fields of s.c.t. [spinocervical tract] neurons and the columnar organization of hair follicle afferent fiber terminals in the spinal cord. The receptive fields of most s.c.t. neurons apparently are defined by their connexions with hair follicle afferent fibers such that, along the mediolateral axis, spatial separation of the dendritic trees of s.c.t. neurons is crucial for receptive field separation.