HIPPOCAMPAL EVENT-RELATED POTENTIALS TO PITCH DEVIANCES IN AN AUDITORY ODDBALL SITUATION IN THE CAT - EXPERIMENT-I

Hippocampal event-related potentials (ERP) in the areas CA1, CA3, and dentate fascia (Df) were recorded in cats during an oddball situation when pitch deviant tones occurred in a series of standard tones. When difference waves were calculated by subtracting ERPs to the standard t ones from those to the deviant tones, no clear N40d, corresponding to a cat analogue of the human mismatch negativity (MMN) observed in earl ier studies, could be detected. Instead, a prominent later negativity (N130d) was observed. A possible extra-hippocampal source of the proce ss reflected by the MMN-like negativity, and a relation between an ori enting response (OR) and the N130d are discussed.