Kindled seizures during a critical post-lesion period exert a lasting impact on behavioral recovery

The present study was undertaken to assess the effects of amygdala kindling on behavioral recovery following unilateral frontal cortex damage in rats. Daily electrical stimulation of the amygdala began 48 h after lesion and continued until all animals had a single Stage 5 seizure. When amygdala kindled seizure activity ratable as Stage 0 occurred within the first 6 days after lesion, animals recovered from somatosensory asymmetries in approximately 3 weeks. In contrast, kindled animals that experienced Stage 1 seizure activity within the first 6 days after lesion failed to recover from somatosensory deficits in 4 months of testing. Differences in rate of recovery could not be accounted for by lesion size or placement. These data support the notion that not only is there a ‘critical period’ after brain damage during which the recovery process is vulnerable to seizure activity, but the type of kindled seizure that is experienced during that time ultimately determines how recovery is affected.