EVENT-RELATED POTENTIALS IN THE DORSAL HIPPOCAMPUS OF RATS DURING AN AUDITORY-DISCRIMINATION PARADIGM

The relation of the hippocampal neuronal activity to the rat event-rel ated potential (ERP) generation was examined during an auditory discri mination oddball paradigm. ERPs were recorded using a linearly-arrange d series of electrodes chronically implanted at the skull, in the fron toparietal cortex, in the CA1 and CA3 regions of the dorsal hippocampu s and in the thalamus. The target tone elicited N40, P100, N200, and P 450 at the skull electrode. The non-target tone, on the other hand, pr ominently evoked only the P100 component. At the intracranial electrod es, the ERP amplitude at the latency of the skull P450 was significant ly greater in the CA? region than that at other recording sires, altho ugh a phase reversal was not observed. The results indicate that the P 450 of the rat may correspond to the human P3, and that the neuronal a ctivity in the hippocampus is involved in its generation.