Several experimental studies have shown that restriction of patterned sensory input during ontogeny produces severe and enduring disruption of sensory processing abilities and adaptive behavior in the mature animal. Abnormalities in adaptive behavior also result from sensory pathway transection at the midbrain level, reticular formation lesions, ablation of frontal cortex, and hippocampal removal in adult subjects. Certain aspects of the behavioral aberrancies associated with these experimental treatments resemble symptoms of infantile autism, childhood hyperactivity, and other clinical disorders associated with sensory processing dysfunctions. This study seeks to examine the neurophysiological bases of normal and abnormal sensory processing in cats. Subjects raised in restricted environments or lesioned in specific brain structures in infancy will be tested behaviorally and electrophysiologically for sensory processing abilities and compared with littermate controls. Behavioral deficits will be related to specific structural and electrophysiological abnormalities in order to determine which functional interractions and electrophysiological processes are necessary during development for normal adaptive sensory processing capacities at maturity.