Cortical plasticity and the development of behavior after early frontal cortical injury

It has been known for over 100 years that frontal lobe injury in children i s often associated with considerably more functional recovery than after si milar injury in adulthood. Systematic study of frontal cortical injury in l aboratory animals has shown that this recovery is tightly tied to developme ntal age: There is a brief window of time during cortical development durin g which the brain is able to compensate. Simply being young is not sufficie nt because injury prior to this critical period leads to miserable behavior al outcomes. For humans, the least favorable time for cortical injury is li kely at the end of the gestational period, perhaps including the Ist month or so of life whereas the most favorable time is around 1 to 2 years of age . In addition to age, the extent of behavioral recovery is influenced by ag e at assessment, the nature of the behavioral assessment, sex, and lesion s ize. Anatomical studies have shown that functional recovery following early cortical injury is correlated with a reorganization of remaining cortical circuitry, including increased dendritic arborization and increased spine d ensity. Recovery, and the compensatory anatomical changes, can also be pote ntiated by application of different treatments including behavioral therapy , trophic factors, and neuromodulators. Finally, there is preliminary evide nce in laboratory animals to suggest that it may be possible to induce neur al regeneration in the injured brain and that the regenerated brain functio ns to support functional recovery.