HIPPOCAMPAL EVOKED-POTENTIALS TO PITCH DEVIANCES IN AN AUDITORY ODDBALL SITUATION IN THE RABBIT - NO HUMAN MISMATCH-LIKE DEPENDENCE ON STANDARD STIMULI

Hippocampal auditory evoked potentials (AEP) were recorded in 10 rabbi ts when pitch deviant tones occurred in a series of standard tones (od dball situation). In control recordings, deviant tones were presented without intervening standard tones (deviant-alone situation). All AEP deflections observed in the oddball situation were found also in the d eviant-alone situation. Thus, it appeared that none of the AEP deflect ions to deviant tones in the oddball situation was specific to a memor y trace of preceding standard tones. This observation was in contradic tion to such a specificity of the mismatch negativity (MMN) found in h umans. Instead, a connection to a neuronal orienting reaction interpre tation was shown to be apparent. A need for additional control procedu res revealing a contribution of neural orienting responses in animal M MN experiments is discussed.