The study of postnatal and later development of the taste and olfactory systems using the human brain mapping approach: An update

Gustatory and olfactory functions are already present at birth, although the full development of both systems takes place postnatally. The existence of early postnatal sensitive periods throughout the developmental course of sensory systems, including the taste and olfactory, has been well documented. The normal postnatal and later development of any sensory function parallels development of the central nervous system. This development is associated with development-related plastic changes that ensure the increasing efficiency of neural communication that takes place throughout development and correlates with signal changes acquired by means of neuroimaging techniques. In this paper, we review papers published in the last 10 years that have reported on the investigation of age-related changes in brain activation patterns in response to gustatory and olfactory processing with two related aims. We aim to ascertain the way in which developmental plastic changes within the taste and olfactory systems have been reflected in signals obtained through neuroimaging techniques. Furthermore, we aim to identify sensitive periods of gustatory and olfactory development by conducting a systematic review of research on brain activation patterns of the taste and olfactory systems that have been measured through neuroimaging techniques in developing populations. The main contribution of the present review is the identification of the need to conduct further research on developmental brain mapping of the taste and olfactory systems in newborns, children and adolescents, and on the association between developmental plastic changes and imaging signals. In addition, further developmental research based on longitudinal designs is required.