On different patterns of dendritic bundling in the cerebral cortex of the cat

Summary

In frontal, horizontal and sagittal paraffin sections through the cat's brain regional differences in the pattern of dendritic bundling have been investigated. It is shown that in the gyrus splenialis and suprasplenialis 2–5 apical dendrites of layer IV pyramids approach each other to form vertical bundles which run straight through layer IV. In the posterior sigmoid gyrus, on the other hand, most apical dendrites arising from the pyramidal cells bifurcate immediately above layer V and give rise to obliquely running branches which cross each other before turning upwards and joining other dendrites to take part in the formation of bundles. In this region the dendritic tree of the pyramidal cells seems to be characterized by an unexpectedly high degree of directional specialization.—In functional terms the findings can be summarized by stating that in the visual and sensorimotor regions of the cat's cerebral cortex basic differences exist in the relation between the apical dendrites of layer V pyramids.