Event Abstract Back to Event Acoustic change processing in fetuses: a fMEG study Tamara Matuz1, Jana Muenssinger2*, Adrian Furdea1, R B Govindan3, Pamela Murphy3, Maureen Ware3, Jessica R. Temple3, Curtis L. Lowery3, Hari Eswaran3 and Hubert Preissl3, 4 1 University of Tuebingen, Institute of Medical Psychology and Behavioral Neurobiology, Germany 2 University of Tuebingen, Germany 3 University of Arkansas for Medical Sciences, Department of Obstetrics and Gynaecology, United States 4 University of Tuebingen, MEG and fMEG Center, Germany To date, fetal magnetoencephalographic studies have used pure or harmonic tones in standard oddball paradigms to assess central auditory processing and to investigate the basic cognitive function of sound discrimination. The aim of our study is to determine whether the sensitivity to spectral width and loudness of sound observed in newborns [1] is also present in fetuses. For this purpose, we have used white noise (WN) segments for the first time in fetal recordings. Ten fetuses (GA 33-36 weeks) were tested in two auditory oddball conditions, each consisting of a standard stimulus (probability of 0.8) and two infrequent deviant stimuli (0.1 probability each). WN (120 db), a 500Hz tone (120 db) and an attenuated WN (90 db) were used. In the first oddball condition (C1), a stream of attenuated WN (standard) was intermixed with the 500Hz tone (deviant 1) and the WN segment (deviant 2). In the second condition (C2), a stream of 500Hz tones (standard) was occasionally broken by attenuated WN (deviant 1) and WN (deviant 2). We compared the ERs elicited by the infrequent WN segments with those elicited by the infrequent attenuated WN (loudness change) and the infrequent 500Hz tones (spectral change). Detectable auditory ERs could be found in eight out of ten fetuses in C1 and in five out of ten in C2. ERs were determined based on visual inspection. Results show that amplitudes of ERs elicited by infrequent WN segments were not significantly different than of those elicited by the infrequent 500Hz tones (Z= -.70, p = 0.4; Wilcoxon Test). However, we found a trend toward significance regarding the difference between the amplitudes of ERs elicited by the WN segments and those elicited by attenuated WN (Z= -1.8, p = 0.08; Wilcoxon Test). These preliminary outcomes suggest that loudness change rather than spectral change influences the amplitudes of auditory ERs. Final results, including a statistical validation of determined ERs using a bootstrap approach are to be presented.