Figure 8. Experiment 2 glutamatergic agonist effect on exposed rats with no evidence of tinnitus (triangular data points).

The results of unexposed and exposed control groups are depicted as in Figure 7. Pre-drug data are shown in the upper left panel. The agonist cocktail induced significant tinnitus in the exposed no-tinnitus animals, indicated by a function down-shift (upper right panel) after 300 hrs of treatment, but their tinnitus did not attain the same level as the exposed group with tinnitus (F statistics in panel). Nevertheless, the agonist-induced tinnitus persisted for at least 30 days post drug (lower right panel), at which time testing was discontinued.