Distribution of Cortical "Feedback" Fibers in the Nuclei Cuneatus and Gracilis.

Abstract

In cats the cortical fibers to the nuclei cuneatus and gracilis were found to distribute primarily to those parts of the nuclei, containing multipolar cells possessing long sparsely ramifying dendrites. The cells with complicated dendritic trees (caudal cell clusters) receive only very few cortical fibers. Preliminary evidence suggests that medical lemniscus transsection affects some of the former cells less severely than the latter, suggesting differences in the number of collaterals maintained by the respective cells. A comparison with physiological findings suggests that the cutaneous receptive fields of some of the former cells are larger than those of the latter. Therefore, it may be asked whether the cortical feedback might function in relation to the localizing resolution power of this sensory system.