Cerebral Maturation and Functional Imaging

Abstract

Normal cerebral maturation and therefore development of sensory and cognitive functions are sustained by neurobiological changes that are better known in animals than in humans. Postnatal developmental changes can now be approached in humans by means of non-invasive methods using external detection of brain signals. These cerebral functional imaging techniques include PET (positron emission tomography), SPECT (single photon emission computed tomography) and fMRI (functional magnetic resonance imaging). PET and fMRI recently experienced rapid development for stimulation studies because they can detect and localize the activation produced in the brain by selective cognitive tasks. Unfortunately, technical constraints make such studies almost impossible to realize in children. PET and SPECT can also measure at rest, respectively the local metabolism for glucose and regional cerebral blood flow, both parameters being proportionally close to the neuronal activity in the same region. These “at rest studies” are available in young children and are now being used in pathological conditions such as childhood epilepsy or developmental disorders. Most of the data available about postnatal functional brain maturation have been obtained by PET and SPECT “at rest studies”. They have the advantage of providing measures at the regional level. It is therefore interesting to correlate the regional changes in metabolism or in cerebral blood flow during maturation with the development of sensory and cognitive functions in humans.