Dendritic development in neocortex of children with mental defect and infantile spasms

The Golgi-Cox method was used to analyze the dendritic spread of pyramidal neurons in middle frontal gyrus of 11 patients with mental defect. Abnormalities in dendritic development were found in five profoundly retarded children at ages one to four years. Four had a history of infantile spasms and an EEG tracing characterized as “hypsarrhythmia” in addition to amentia. Histologic abnormalities included decrease in length of basal dendrites, decreased secondary branches, and—in the miost severely affected—a decrease in branches arising directly frorn the perikaryon. Horizontal and tangential branches of apical dendrites also were reduced in number and length. The method failed to detect abnormalities in frontal cortex from several older retarded individuals. The results suggest that defective growth of cortical dendrites is common in the severely retarded. Limitations of the Golgi method may account for failure to detect abnormalities in less retarded patients and in older patients.