Double origin of the pericellular baskets of the pyramidal cells of the human motor cortex: A Golgi study

Abstract

The structure, intracortical distribution and orientation of a special type of basket-forming afferent fiber from the motor cortex of a 2.5-day-old infant is presented. The existence of these fibers confirm original observations made by Cajal concerning the origin of the pericellular baskets of the human motor cortex. It is concluded from this study that the pericellular baskets formed around the bodies of the giant pyramidal neurons of layer V (and possibly of lower layer III) of the human motor cortex have a double origin from intrinsic and extrinsic sources. The intrinsic component of these pericellular baskets is furnished by a special type of stellate interneuron previously described and named the cortical basket cell. The extrinsic component is furnished by the basket-forming afferent fibers described in this communication. Both of these subsystems are similarly distributed and oriented within narrow vertical planes perpendicular to the long axis of the precentral gyrus of the motor cortex. The dimensions of the planes determined by the intracortical distribution of these two subsystems are also similar. It is suggested that there is a close anatomical and possible functional interrelationship between these two subsystems of the motor cortex. Although the origin of these basket-forming afferent fibers is unknown it is postulated that they may originate in the projective neurons of the nucleus ventralis lateralis of the thalamus and that they may be part of the cerebello-thalamo-cortical pathway.