Abstract
In the second report, we have already clarified that the response to hypothermia differs in each turn and the transient increase in AP amplitude is due to the increased response originating from the basal turn. Concerning this peculiar manner of AP amplitude, we suspected the olivocochlear bundle (OCB) to be involved. Therefore, the effect of transection of OCB upon AP was examined. No significant change was found in the threshold and latency of AP, but the AP amplitude was slightly increased after the transection of OCB. When the animal was cooled after the transection of uncrossed OCB, the transient increase in the AP amplitude was not remarkable, but there was no statistically significant difference from that in non-section cases. In the case of cooling after the transectian of the crossed and uncrossed OCB, however, the AP amplitude demonstrated almost linear decrease as a function of temperature decline. With these results, we concluded that the transient increase of AP amplitude during hypothermia was due to the elimination of the inhibitory effect by OCB.
