Evoked cortical potentials in prenatally irradiated rats

Abstract

The direct cortical, callosal, specific-sensory and interhemispheric responses have been evoked in mature cortex of rats x-irradiated on the nineteenth and twenty-first days of gestation (a procedure which prevents the development of layers II, III, and IV). In general, responses recorded from the cortex of animals irradiated on the twenty-first day of gestation exhibit increased conduction velocities lowered thresholds, and raised amplitude. Threshold is also lowered in rats irradiated on the nineteenth day of gestation although the recorded responses tend to be very variable and to demonstrate normal or lowered amplitude and slowed or normal conduction velocities. The afterdischarge of responses in both groups of animals remains normal and appears to be conducted without decrement over the distances studied. Attenuation of the direct response with distance from the point of stimulation is increased as a result of irradiation on the nineteenth day of gestation but is normal in the group irradiated later in life.