Fig. 2.

Experimental design. The goal was to isolate outer hair cells (OHCs), inner hair cells (IHCs), and neural sources of the summating potential (SP). To do this, animals with two hearing conditions were used. In step 1, recordings were made from normal hearing (NH) animals with the full complement of OHCs, IHCs, and neural elements or from animals treated with a combination of furosemide and kanamycin (FK), which had OHCs removed. In step 2, the neurotoxin kainic acid (KA) was applied and the recordings repeated. The response contributed by IHCs was isolated directly in FK animals after KA. Subtractions within groups (step 1 – step 2; arrows) yield the neural responses, whereas subtractions between groups (NH – FK; arrowheads) yield the OHC responses. The boxes indicate the resulting subtractions used to quantify the neural, IHC, and OHC responses (see text).