Functional development of the visual system in human fetus using magnetoencephalography

The development of the human brain in utero is normally regarded as a dynamic process involving mainly structural and quantitative changes in neurons and their distribution. However, it is generally accepted that a parallel development of functional specialization occurs in certain areas of the brain, especially in the primary cortex. Nearly all knowledge of functional fetal brain development has been obtained from various animal studies rather than human studies. These studies show that the primary sensory areas like auditory, visual, and somatosensory cortex show a basic function similar to that of a fully developed brain. It has been specifically shown that the visual system develops during fetal life and becomes functional before birth. Several studies have demonstrated the feasibility of using visual evoked response (VER) recordings on preterm human infants to follow the functional development of the visual system. With the advent of the noninvasive technique of magnetoencephalography (MEG), human fetal VER recordings are now possible thus providing the opportunity to track its functional development with gestation. We present and discuss the results of VER recordings in human fetuses starting at 28 weeks of gestation performed using a 151-channel MEG system.