Auditory evoked potentials to changes in speech sound duration in anesthetized mice
Electrophysiological response termed mismatch negativity (MMN) indexes auditory change detection in humans. An analogous response, called the mismatch response (MMR), is also elicited in animals. Mismatch response has been widely utilized in investigations of change detection in human speech sounds in rats and guinea pigs, but not in mice. Since e.g. transgenic mouse models provide important advantages for further studies, we studied processing of speech sounds in anesthetized mice. Auditory evoked potentials were recorded from the dura above the auditory cortex to changes in duration of a human speech sound /a/. In oddball stimulus condition, the MMR was elicited at 53-259 ms latency in response to the changes. The MMR was found to the large (from 200 ms to 110 ms) but not to smaller (from 200 ms to 120-180 ms) changes in duration. The results suggest that mice can represent human speech sounds in order to detect changes in their duration. The findings can be utilized in future investigations applying mouse models for speech perception.