DIPOLE LOCALIZATION AND TEST-RETEST RELIABILITY OF FREQUENCY AND DURATION MISMATCH NEGATIVITY GENERATOR PROCESSES

The mismatch negativity (MMN) is an event related potential component elicited by changes in duration, frequency or intensity of the stimuli during repetitive series of equal standard stimuli. In the present st udy we compared duration and frequency MMN using dipole source analysi s concerning both the test-retest reliability of MMN-amplitudes and th e locations of the potential sources. Furthermore, the influence of at tention for test-retest-reliability was studied. Therefore, two groups of healthy subjects were investigated with different attentional mani pulations. Twenty-one healthy subjects had to perform a visual attenti on task during the recording and 21 healthy subjects had no additional task to perform. All subjects were studied twice with a time interval of 3 weeks. Test-retest reliability was sufficiently high for the fre quency but slightly lower for the duration MMN. The locations of the f requency and duration MMN-dipoles were in the auditory cortex with a m ore anterior and caudal location for the frequency MMN-dipoles. The la tter finding supports the hypothesis that the frequency and duration M MNs have separate neuronal generators.