Behavioral and hippocampal evoked responses in an auditory oddball situation when an unconditioned stimulus is paired with deviant tones in the cat: Experiment II

Event-related potentials (ERP) in the areas CA1, CA3 and dentate fascia (Df) of the hippocampal formation were recorded during an oddball situation in the cat. A rewarding electrical stimulation of the lateral hypothalamus (US) was paired with deviant tones (2500 Hz) that occurred randomly in a series of the standard tones (2000 Hz) given to the left ear. In addition to developing orienting head movements to the side of the deviant tones, an increase in the amplitude of parallel hippocampal ERPs was observed. Both the behavioral and neural responses appeared not until a 50 ms latency range. Furthermore, time-amplitude characteristics of the ERPs corresponded to time-acceleration characteris…

ERPs to pitch changes: a result of reduced responses to standard tones in rabbits.

EVENT-RELATED potentials (ERPs) were recorded in rabbits when pitch deviant tones occurred in a series of standard tones (oddball situation). In control recordings, the deviant tones were presented without the standard tones (deviant-alone situation). In the oddball situation, significant difference ERPs (deviant ERPs - standard ERPs) could be found in the hippocampal and cerebellar recordings but not in the visual cortex. All the ERPs to the deviant stimuli observed in the oddball situation were also present in the deviant-alone situation. The difference ERPs were therefore based on reduced responses to the standards. The results are discussed in the context of a mismatch negativity (MMN) …

Hippocampal responses to pitch deviant tones in rabbits

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 tones from those to the deviant tones, no clear N40d, corresponding to a cat analogue of the human mismatch negativity (MMN) observed in earlier studies, could be detected. Instead, a prominent later negativity (N130d) was observed. A possible extra-hippocampal source of the process reflected by the MMN-like negativity, and a relation between an orienting response (OR) and the N130d are discussed.

Multiple-unit responses to pitch changes in rabbits

Multiple-unit activity (MUA) was recorded from the hippocampus (Hc), the visual cortex (VCx) and the cerebellar cortex (CerCx) in rabbits when pitch deviant tones were presented in a series of standard tones (oddball situation) and when standard tones were absent (deviant-alone situation). Significant MMN-like responses (deviant responses minus standard responses in the oddball situation) occurred in Hc, reflecting a MUA increase to the standards and its decrease to the deviants. In accordance with parallel ERPs reported earlier, the MMN-like responses reflected responses only to different presentation frequencies of stimuli. Non-selectivity in the pitch of such responses in VCx and a lack …