Effects of tectal slits on the anomalous corticotectal fibres

Following cortical lesion and a mid-saggital cut through the tectum in newborn albino rats, the remaining intact cortex was seen to project bilaterally to the superior colliculus with anomalous fibres running across the mid-line to the contralateral superior colliculus. In animals lesioned at day 5 postnatally and later, the anomalous fibres were mostly deflected by the scar tissue resulting from the tectal injury. In animals lesioned within the first 2 days after birth, a good proportion of the anomalous fibres coursed through the scar tissue. In all animals studied except one the pattern of terminations of the anomalous fibres was in agreement with the observations of Leong and Lund.