Abstract 109

Aim To assess the activation of the primary olfactory cortex in newborn infants receiving olfactory unpleasant stimuli (a detergent used to remove tape form the skin). Methods Oxyhaemoglobin [Hb O2] and deoxyhaemoglobin [Hb H] changes were monitored in three at- term newborns by Near infrared spectroscopy - NIRS (NIRO 300, Hamamatsu Photonics, Japan). Two couples of optodes were used, each placed above the anterior orbito-frontal gyri, with the light source 4 cm apart from the detector. A cotton swab soaked in the detergent solution, represented the unpleasant smell. Parental consent, and ethic Committee approval were obtained for all cases. Results In all babies a decrease in the [Hb O2] on the right side, but not on the left, was registered in response to the unpleasant smell. In contrast, in response to pleasant smells (breastmilk, vanilla), the left cortex is activated. No changes were observed in the [Hb H]. The decrease in the [Hb O2] was followed by a temporary increase before the stabilisation on the baseline. No differences were monitored in heart rate, respiration, and O2 saturation. Conclusion The present findings lead us to speculate that an uncoupling between function and cerebral blood flow could occur in the cortical olfactory region, and that the right hemisphere appears to be involved in processing unpleasant smells, and there is a difference between processing of pleasant and unpleasant stimuli.