Sound level dependence of auditory evoked potentials: simultaneous EEG recording and low-noise fMRI

Herrmann, C. S.¹, Thärig, S.¹, Behne, S.², Schadow, J.¹, Lenz, D.¹, Scheich, H.², and Brechmann, A.^2
1Lehrstuhl Biologische Psychologie, Otto-von-Guericke Universität Magdeburg; ²Leibniz-Institut für Neurobiologie, Magdeburg

A problem for the analysis of auditory processing in fMRI is the noisy environment. While EEG studies outside an MRI scanner repeatedly demonstrated a clear sound level-dependent increase of N1 amplitude, this finding was less obvious in simultaneous recordings inside a scanner. Since this inconsistency might be due to the confounding effect of the EPI noise, we employed a low-noise protocol in combination with simultaneous EEG recordings. Frequency modulated tones (FM) were presented monaurally at two sound intensities. Our results replicate the sound level dependence of AEPs from previous EEG studies, i.e. a significant shortening of N1 latency and an increase in the N1-P2 amplitude for the higher sound intensity. The louder stimulation yielded more activated voxels in fMRI and stronger activations. Our results suggest that low-noise sequences might be advantageous for the examination of auditory processing in simultaneous EEG and fMRI recordings.

Symposium 20: Recent Advances in EEG-fMRI Integration
12.06.2009, 14:00-15:00
Seminarraum 11