A Golgi study of cell morphology in the deep layers of the human superior colliculus

The superior colliculus is a morphologically and functionally complex center for integration of sensory and motor information which is utilized to orient the head and eyes toward stimuli in the environment. Recent studies have suggested that some of the afferent and efferent fiber pathways of the intermediate and deep layers are associated with particular populations of neurons as identified by size, shape and location. Immuno-cytochemical studies suggest a regional distribution of certain putative neurotransmitters in the superior colliculus. In the present Golgi study of the human superior colliculus, neurons of the stratum griseum profundum and stratum album profundum have been classified according to shape of soma and orientation of soma and dendritic tree, into five discrete cell populations, each with its own set of characteristics: (1) horizontal cells, (2) vertical cells, (3) pyramidal cells, (4) inverted pyramidal cells, and (5) stellate cells. The distribution of these identified cell populations within the collicular laminae, and the distribution of cell processes have been determined in order to provide a basis for correlation with previous anatomical, electrophysiological and immunocytochemical studies. In addition, the present study provides a substrate for evaluating possible channels of communication within the superior colliculus and between deep collicular laminae and the periaqueductal gray matter.