The neural mechanisms of deviancy and target detection
were investigated by combining high density event-related
potential (ERP) recordings with functional magnetic resonance
imaging (fMRI). ERP and fMRI responses were recorded using
the same paradigm and the same subjects. Unattended deviants
elicited a mismatch negativity (MMN) in the ERP. In the
fMRI data, activations of transverse/superior temporal
gyri bilateral were found. Attended deviants generated
an MMN followed by an N2/P3b complex. For this condition,
fMRI activations in both superior temporal gyri and the
neostriatum were found. These activations were taken as
neuroanatomical constraints for the localization of equivalent
current dipoles. Inverse solutions for dipole orientation
provide evidence for significant activation close to Heschl's
gyri during deviancy processing in the 110–160-ms
time interval (MMN), whereas target detection could be
modeled by two dipoles in the superior temporal gyrus between
320 and 380 ms.