CEREBRAL MORPHOLOGY AND FUNCTIONAL SPARING AFTER PRENATAL FRONTAL-CORTEX LESIONS IN RATS

Rats were given suction lesions of the presumptive frontal cortex on e mbryonic day 18 (E18) and subsequently tested, as adults, on tests of spatial navigation (Morris water task, radial arm maze), motor tasks ( Whishaw reaching task, beam walking), and locomotor activity. Frontal cortical lesions at E18 affected cerebral morphogenesis, producing unu sual morphological structures including abnormal patches of neurons in the cortex and white matter as well as neuronal bridges between the h emispheres. A small sample of E18 operates also had hydrocephaly. The animals with E18 lesions without hydrocephalus were behaviorally indis tinguishable from littermate controls. The results demonstrate that an imals with focal lesions of the presumptive frontal cortex have gross abnormalities in cerebral morphology but the lesions leave the functio ns normally subserved by the frontal cortex in adult rats unaffected. The results are discussed in the context of a hypothesis regarding the optimal times for functional recovery from cortical injury. (C) 1998 Elsevier Science B.V. All rights reserved.