Complete sparing of spatial learning following posterior and posterior plus anterior cingulate cortex lesions at 10 days of age in the rat.

Neonatal posterior cingulate cortex lesions spare the spatial deficits that characterize adult lesions. The present experiments examined the possibility that the anterior cingulate cortex mediates the spared spatial behavior. Rats were given bilateral lesions of the posterior cingulate cortex or anterior plus posterior cingulate cortex on postnatal days 4 (P4), 10 (P10), or in adulthood (P120). All groups were tested for spatial learning on the Morris place task in adulthood. Adult animals were impaired on place learning relative to controls whereas place learning was spared in all the neonatal groups and sparing was complete in the group receiving day 10 lesions. The results are discussed in relation to neural mechanisms, including fiber rerouting, synaptic changes and generation of new neurons, that may mediate spared spatial following neonatal posterior cingulate cortex lesions. Also discussed is evidence indicating that the neonatal brain, especially the day 10, has a special ability to compensate for injury.