Interpretation of neuromagnetic responses: two simple models for extended current sources in the human auditory cortex.

The usefulness of dipole models in interpreting neuromagnetic field patterns was studied. By statistical means it turned out to be difficult to differentiate between a point-like source and an extended source at the auditory cortex. A single dipole is an appropriate source model for localized cortical activity extending up to a few square centimeters. Additional information about the source configuration can be obtained by focusing the analysis on areas where the differences between patterns produced by different sources should theoretically be the largest.