OLFACTORY PERCEPTION AND OLFACTORY EVENT-RELATED POTENTIALS IN NEWBORNS WITH 3M SYNDROME

3M syndrome is a rare autosomal recessive dwarfism syndrome. The distinctive features of this syndrome are related to a limitation of prenatal growth, facial dysmorphism, the absence of microcephaly and absence of mental impairment. The subjects affected by this form of disorder often have respiratory problems and present different facial morphology (i.e., fleshy nose, antero-verse nostrils) [1]. The aim of this research was to investigate how the 3-M syndrome could have implications in the olfactory system. No study has so far been conducted on 3M to evaluate the use of olfactory event related potentials (OERP) as tools for investigating the functional response to chemical stimulation. Materials and Methods 3 male siblings, diagnosed as 3M syndrome, [2 newborns twins of 4 months old (3M-N) and a 3M 18 months old (3M-O)], were compared with two controls couple of twins (HS), matched by age and sex. The subjects performed an olfactory recognition task. The scent was administered through the device US2017127971 (A1) [2], with 20 μL of Eucalyptus. The paradigm of presentation corresponds to the stimulation of OERP. The analysis considered the olfactory components N1 and LPC [3], the wavelet and the connectivity values. Results The subject 3M-O shows, on N1, greater amplitudes (average amplitude 3M V -45 vs HS V -25) e delayed latencies (average latency 3M 440 ms. vs HS 200 ms) and on LPC greater amplitudes (3M-O V +17,5 vs HS V +5) and faster latencies (3M-O 260 ms vs HS 380 ms). The LPC data concern the response obtained in the right fronto-lateral area. Through the brain mapping it appears that the 3M-O subject shows a greater left lateralization. The 3M-N twins show, on both N1 and LPC, smaller amplitudes (N1: 3M-NV-17,5 vs HS V18,5; LPC: 3M-N V10 vs HS V 22,50) and delayed latencies (N1:3M-N 350 ms. vs HS 225 ms; LPC: 3M-N 220 ms vs HS 340 ms). Within the range between 70ms - 250ms, there is almost minimal activation of the parietal area in the case of 3M-N twins. In the range between 250ms to 420ms, 3M-N and 3M-O subjects showed an activation of part of the left hemisphere, of the parietal and of the left occipital area; while the HS showed an activation of parietal, left frontotemporal and right occipital areas. The wavelet analysis shows greater connectivity in alpha and delta in the case of the subject 3M-O and 3M-N vs HS. Conclusions In 3M syndrome, the olfactory processing seems to be clearly diversified (see Fig.1). In particular, the differences in the N1 and LPC components indicate substantial differences in 3M syndrome that can modify the pattern of olfactory processing. Moreover, the 3M subjects, in addition to greater connectivity, show different localizations of arousal due to olfactory stimulation, highlighting the implication of much larger areas ranging from the left hemisphere to the right hemisphere including occipital localizations.