Early Brain Injury, Plasticity, and Behavior

Abstract

Brain development progresses through a series of steps that are genetically programmed but influenced significantly by environmental events, including injury. The morphological and functional effects of brain perturbations during development vary qualitatively with the precise embryological events occurring at the time of injury. Recovery is especially poor if the cortex is injured immediately following the completion of neurogenesis, and is especially good if injury occurs during the time of maximum astrocyte proliferation and synapse formation. The young injured brain is especially sensitive to environmental events, and recovery thus can be enhanced by various forms of stimulation such as tactile stroking in infancy and complex housing as juveniles and adolescents. Recovery is also modulated by gonadal hormones and by neuromodulators (noradrenaline and acetylcholine).