NEURONAL DEVELOPMENT AND ONTOGENY OF EVOKED POTENTIALS IN AUDITORY AND VISUAL CORTEX OF DOG

Using chronically implanted electrodes in the visual and auditory cortex, the development of evoked responses was studied in restrained but unanesthetized dogs of various ages. Neuronal development was evaluated from Golgi-Cox preparations of visual and auditory cortex. Development of both visual and auditory evoked responses was rapid during the first 3 weeks of life, attaining relatively mature characteristics by 4-5 weeks. Similarly, neuronal development in both cortical areas approximated adult complexity by 4-5 weeks, the most rapid development occurring during the first 3 weeks in both the deeper and more superficial cell layers. Subsequent developmental changes after 5 weeks were more gradual, and contrasted the rapid development of all parameters studied during the period from birth to 3 weeks of age. The significance of qualitative differences in the ontogeny of visual and auditory evoked responses and of the different neuronal layers is discussed. © 1968.