Recovery of function after neonatal ablation of the auditory cortex in rats (Rattus norvegicus)

Functional recovery following neonatal ablation of the auditory cortex was surveyed in 28 rats. Fourteen neonatal-lesioned rats had their temporal cortex lesioned on the date of birth (P1); 7 adult-lesioned rats had their auditory cortex lesioned at P60; and 7 rats served as controls. The training consisted of two phases using task with a Go/No Go procedure. The first task was to detect the presentation of a tone pulse. The second task was to discriminate the pulse rate of a tone pulse. Results showed that the achievements of neonatal-lesioned and control groups were comparable in both tasks. Adult-lesioned rats, however, failed to discriminate temporal patterns, although they could detect tone presentation as efficiently as the other two groups. These findings suggested that discrimination of temporal patterns could be a critical function of the auditory cortex and that brain injury in infancy was more compensated than the comparable damage in adulthood. Neurological plasticity was suggested in the recovery of function in our neonatal-lesioned animals.