A small lesion was placed in the rat somatosensory vibrissa cortex on postnatal days (PND) 0, 5, 10, 14 or 20. At the age of three months, the animals were sacrificed and tangential sections of the somatosensory cortex were reacted for detection of succinic dehydrogenase or cytochrome oxidase activity to see if the lesion had produced a defect in the barrelfield. In animals of the groups of PND 0, 5 and 10, the entire barrelfield formed normally, but avoided the lesioned cortex. In a few cases, however, the lesion was found between rows of barrels but never between arcs of barrels. This latter type of result was seen only in the PND-0 group. In animals of the groups of PND 14 and 20, the lesion typically resulted in a defect in the barrelfield. It is concluded that the vibrissa cortex attains its final topographic specificity between day 10 and 14 postnatally. In view of the date of barrelfield formation in normal animals (postnatal day 5), it is thought that the barrelfield is subject to plastic reorganization for some days after its formation; at least for the period between postnatal days 5 and 10.
The effect of differential rearing on evoked potentials was studied in the vibrissal representation of the rat neocortex. Young rats were reared in either enriched, standard, or impoverished conditions from the age of 24-25 days. At 55-60 days of age, the epicortical responses to electric stimulation of a whisker follicle were analyzed under urethane anesthesia. Slight but significant shortening of the latency of initial positivity in the evoked potential was observed after rearing in the enriched condition as compared to the data obtained from the littermates that were reared in the standard or impoverished conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.